Method and apparatus for determining HARQ timing in wireless communications

ABSTRACT

Sidelink downlink control information may include a first indicator field that indicates a sidelink hybrid automatic repeat request (HARQ) feedback timing. A bitwidth of the first indicator field may be based on at least one of one or more parameters from the base station. The first wireless user device may transmit, based on the SL DCI and to a second wireless user device, a first sidelink signal. The first wireless user device may receive, during a first time interval and from the second wireless user device, first sidelink HARQ feedback information responsive to the first sidelink signal. The first wireless user device may determine, based on the sidelink HARQ feedback timing and based on the first time interval, a second time interval. The first wireless user device may transmit, during the second time interval and to the base station, the first sidelink HARQ feedback information.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2019-0095768 filed on Aug. 6, 2019, which is herebyincorporated by reference in its entirety.

BACKGROUND 1. Field

The present disclosure may provide a method and apparatus for wirelesscommunications. One or more devices may determine a Hybrid AutomaticRepeat Request (HARQ) timing in wireless communications, such as newradio (NR) vehicle-to-everything (V2X) communications and any otherwireless communications.

2. Discussion of the Background

International Mobile Telecommunication (IMT) framework and standard havebeen developed by the International Telecommunication Union (ITU). Also,continuous discussion for 5-th generation (5G) communication is ongoingthrough a program called “IMT for 2020 and beyond”.

To satisfy the requirements requested by “IMT for 2020 and beyond”,various proposals have been made to support various numerologies about atime-frequency resource unit standard by considering various scenarios,service requirements, and potential system compatibility in a 3-rdGeneration Partnership Project (3GPP) new radio (NR) system.

Vehicle-to-everything (V2X) communication may include a communicationmethod of exchanging or sharing road infrastructures during driving andinformation, such as traffic conditions, through communication withother vehicles. V2X may include, for example, vehicle-to-vehicle (V2V),which may refer to long term evolution (LTE)-based communication betweenvehicles, vehicle-to-pedestrian (V2P), which may refer to LTE-basedcommunication between a vehicle and a user equipment (UE) carried by auser, and vehicle-to-infrastructure/network (V2I/N), which may refer toLTE-based communication between a vehicle and a roadside unit(RSU)/network. The RSU may be a transportation infrastructure entityconfigured by a base station or a fixed terminal, such as, an entitythat transmits a speed notification to a vehicle.

Low latency and high reliability may need to be secured for V2Xcommunication services. To secure low latency and high reliability inV2X communication services, various examples including determining aHARQ feedback transmission timing in the case of transmitting HARQfeedback information in V2X communication will be described herein.

SUMMARY

Sidelink downlink control information may include a first indicatorfield that indicates a sidelink hybrid automatic repeat request (HARQ)feedback timing. A bitwidth of the first indicator field may be based onat least one of one or more parameters from the base station. The firstwireless user device may transmit, based on the SL DCI and to a secondwireless user device, a first sidelink signal. The first wireless userdevice may receive, during a first time interval and from the secondwireless user device, first sidelink HARQ feedback informationresponsive to the first sidelink signal. The first wireless user devicemay determine, based on the sidelink HARQ feedback timing and based onthe first time interval, a second time interval. The first wireless userdevice may transmit, during the second time interval and to the basestation, the first sidelink HARQ feedback information.

An aspect of the present disclosure may provide a method and apparatusfor determining a Hybrid Automatic Repeat Request (HARQ) timing invehicle-to-everything (V2X) communication.

An aspect of the present disclosure may provide a method and apparatusthat allows a user equipment (UE) to report sidelink HARQ feedback to abase station in V2X communication.

An aspect of the present disclosure may provide a method and apparatusfor determining a Uu HARQ feedback timing used for a UE to reportsidelink HARQ feedback to a base station.

A method may include transmitting, by a transmitting UE (Tx UE), HybridAutomatic Repeat Request (HARQ) feedback information in a new radio (NR)V2X system. Here, the HARQ feedback information transmission method mayinclude configuring an A/N window through Radio Resource Control (RRC)signaling from a base station, receiving sidelink (SL) DCI from the basestation, transmitting data to a receiving UE (Rx UE) through a sidelinkbased on the SL DCI, receiving sidelink HARQ feedback information aboutthe data from the Rx UE, and reporting to the base station for thesidelink HARQ feedback information received from the Rx UE. Here, thesidelink HARQ feedback information may be transmitted to the basestation in an indicated uplink slot based on SL DCI within the A/Nwindow.

According to the present disclosure, since a Tx UE transmits, to a basestation, HARQ feedback information received from an Rx UE in V2Xcommunication, it may assist a base station to determine a V2Xcommunication resource.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a frame structure for downlink/uplinktransmission.

FIG. 2 illustrates an example of a resource grid and a resource block.

FIG. 3 illustrates an example of a system architecture.

FIG. 4 illustrates an example scenario in which sidelink communicationis performed in a wireless network.

FIG. 5 illustrates an example of a sidelink resource pool.

FIG. 6 illustrates an example of Physical Sidelink Feedback Channel(PSFCH) time resources.

FIG. 7 illustrates an example of PSFCH frequency resources.

FIG. 8 illustrates an example method for reporting sidelink HybridAutomatic Repeat Request (HARQ) feedback.

FIG. 9 illustrates an example method for indicating an uplink timing forreporting sidelink HARQ feedback.

FIG. 10 illustrates an example method for indicating an uplink timingfor reporting sidelink HARQ feedback.

FIG. 11 illustrates an example method for indicating an uplink timingfor reporting sidelink HARQ feedback.

FIG. 12 shows a flowchart illustrating an example method for indicatingan uplink timing for reporting sidelink HARQ feedback.

FIG. 13 illustrates an example method for determining an uplink timingfor reporting sidelink HARQ feedback.

FIG. 14 illustrates an example method for determining an uplink timingfor reporting sidelink HARQ feedback.

FIG. 15 shows a flowchart illustrating an example method for determiningan uplink timing for reporting sidelink HARQ feedback.

FIG. 16 illustrates an example of a correlation between a PSFCH occasionand an uplink slot for transmitting sidelink HARQ feedback.

FIG. 17 shows a flowchart illustrating an example of a correlationbetween a PSFCH occasion and an uplink slot for transmitting sidelinkHARQ feedback.

FIG. 18 shows a configuration of a base station device and a terminaldevice.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Various embodiments of the disclosure will be described more fullyhereinafter with reference to the accompanying drawings such that one ofordinary skill in the art to which the present disclosure pertains mayeasily implement the embodiments. However, the present disclosure may beimplemented in various forms and is not limited to the embodimentsdescribed herein.

In describing the embodiments, detailed description on knownconfigurations or functions may be omitted for clarity and conciseness.Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals are understood to referto the same elements, features, and structures.

It will be understood that when an element is referred to as being“connected to”, “coupled to”, or “accessed to” another element, it canbe directly connected, coupled, or accessed to the other element orintervening elements may be present. Also, it will be further understoodthat when an element is described to “comprise/include” or “have”another element, it specifies the presence of still another element, butdo not preclude the presence of another element uncles otherwisedescribed.

Further, the terms, such as first, second, and the like, may be usedherein to describe elements in the description herein. The terms areused to distinguish one element from another element. Thus, the terms donot limit the element, an arrangement order, a sequence or the like.Therefore, a first element in an embodiment may be referred to as asecond element in another element. Likewise, a second element in anembodiment may be referred to as a first element in another embodiment.

Herein, distinguishing elements are merely provided to clearly explainthe respective features and do not represent that the elements arenecessarily separate from each other. That is, a plurality of elementsmay be integrated into a single hardware or software unit. Also, asingle element may be distributed to a plurality of hardware or softwareunits. Therefore, unless particularly described, the integrated ordistributed embodiment is also included in the scope of the disclosure.

Herein, elements described in various embodiments may not be necessarilyessential and may be partially selectable. Therefore, an embodimentincluding a partial set of elements described in an embodiment is alsoincluded in the scope of the disclosure. Also, an embodiment thatadditionally includes another element to elements described in variousembodiments is also included in the scope of the disclosure.

Further, the description described herein is related to a wirelesscommunication network, and an operation performed in the wirelesscommunication network may be performed in a process of controlling anetwork and transmitting data in a system that controls the wirelesscommunication network (e.g., a base station), or may be performed in aprocess of transmitting or receiving a signal in a user equipmentconnected to the wireless communication network.

It is apparent that various operations performed for communication witha terminal in a network including a base station and a plurality ofnetwork nodes may be performed by the base station or by other networknodes in addition to the base station. Here, the term ‘base station(BS)’ may be interchangeably used with other terms, for example, a fixedstation, a Node B, eNodeB (eNB), gNodeB (gNB), and an access point (AP).Also, the term ‘terminal’ may be interchangeably used with other terms,for example, user equipment (UE), a mobile station (MS), a mobilesubscriber station (MSS), a subscriber station (SS), and a non-APstation (non-AP STA).

Herein, transmitting or receiving a channel includes a meaning oftransmitting or receiving information or a signal through thecorresponding channel. For example, transmitting a control channelindicates transmitting control information or a signal through thecontrol channel. Likewise, transmitting a data channel indicatestransmitting data information or a signal through the data channel.

In the following description, although the term “new radio (NR) system”is used to distinguish a system according to various examples of thepresent disclosure from the existing system, the scope of the presentdisclosure is not limited thereto. Also, the term “NR system” usedherein is used as an example of a wireless communication system capableof supporting various subcarrier spacings (SCSs). However, the term “NRsystem” itself is not limited to the wireless communication system thatsupports the plurality of SCSs.

FIG. 1 illustrates an example of an NR frame structure and a numerologyaccording to an embodiment of the present disclosure.

In NR, a basic unit of a time domain may be T_(c)=1/(Δf_(max)·N_(f)).Here, Δf_(max)=480·10³ and N_(f)=4096. Also, κ=T_(s)/T_(c)=64 may be aconstant about a multiple relationship between an NR time unit and anLTE time unit. In LTE, T_(s)=1/(Δf_(ref)·N_(f,ref)), Δf_(ref)=15·10³ Hz,and N_(f,ref)=2048 may be defined as a reference time unit.

Frame Structure

Referring to FIG. 1 , a time structure of a frame for a downlink/uplink(DL/UL) transmission may include T_(f)=(Δf_(max)N_(f)/100)·T_(s)=10 ms.Here, a single frame may include 10 subframes corresponding toT_(sf)=(Δf_(max)N_(f)/1000)·T_(s)=1 ms. A number of consecutiveorthogonal frequency division multiplexing (OFDM) symbols per subframemay be N_(symb) ^(subframe,μ)=N_(symb) ^(slot)N_(slot) ^(subframe,μ).Also, each frame may be divided into two half frames and the half framesmay include 0˜4 subframes and 5˜9 subframes. Here, half frame 1 mayinclude 0˜4 subframes and half frame 2 may include 5˜9 subframes.

Here, a transmission timing of uplink transmission frame i is determinedbased on a downlink reception timing at a UE according to the followingEquation 1.

In Equation 1, N_(TA,offset) denotes a TA offset value occurring due toa duplex mode difference and the like. Basically, in a frequencydivision duplex (FDD), N_(TA,offset)=0. In a time division duplex (TDD),N_(TA,offset) may be defined as a fixed value by considering a marginfor a DL-UL switching time.T _(TA)=(N _(TA) +N _(TA,offset))T _(c)  [Equation 1]

FIG. 2 illustrates an example of a resource grid and a resource block.

Referring to FIG. 2 , a resource element within a resource grid may beindexed based on each subcarrier spacing. Here, a single resource gridmay be generated for each antenna port and for each subcarrier spacing.Uplink/downlink transmission and reception may be performed based on acorresponding resource grid.

A single resource block may be configured on a frequency domain using 12resource elements and may configure an index n_(PRB) for a singleresource block every 12 resource elements as represented by thefollowing Equation 2. An index of the resource block may be used in aspecific frequency band or system bandwidth.

$\begin{matrix}{n_{PRB} = \left\lfloor \frac{k}{N_{sc}^{RB}} \right\rfloor} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

Numerologies

Numerologies may be variously configured to meet various services andrequirements of the NR system. Also, referring to the following Table 1,the numerologies may be defined based on an SCS, a cyclic prefix (CP)length, and a number of OFDM symbols per slot, which are used in an OFDMsystem. The aforementioned values may be provided to a UE through upperlayer parameters, DL-BWP-mu and DL-BWP-cp (DL) and UL-BWP-mu andUL-BWP-cp (UL).

Also, for example, referring to the following Table 1, if μ=2 and SCS=60kHz, a normal CP and an extended CP may be applied. In other bands, onlythe normal CP may be applied.

TABLE 1 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

Here, a normal slot may be defined as a basic time unit used to transmita single piece of data and control information in the NR system. Alength of the normal slot may basically include 14 OFDM symbols. Also,dissimilar to a slot, a subframe may have an absolute time lengthcorresponding to 1 ms in the NR system and may be used as a referencetime for a length of another time section. Here, for coexistence andbackward compatibility of the LTE and the NR system, a time section,such as an LTE subframe, may be required for an NR standard.

For example, in the LTE, data may be transmitted based on a transmissiontime interval (TTI) that is a unit time. The TTI may include at leastone subframe unit. Here, even in the LTE, a single subframe may be setto 1 ms and may include 14 OFDM symbols (or 12 OFDM symbols).

Also, in the NR system, a non-slot may be defined. The non-slot mayrefer to a slot having a number of symbols less by at least one symbolthan that of the normal slot. For example, in the case of providing alow latency such as an Ultra-Reliable and Low Latency Communications(URLLC) service, a latency may decrease through the non-slot having thenumber of slots less than that of the normal slot. Here, the number ofOFDM symbols included in the non-slot may be determined based on afrequency range. For example, a non-slot with 1 OFDM symbol length maybe considered in the frequency range of 6 GHz or more. As anotherexample, a number of symbols used to define the non-slot may include atleast two OFDM symbols. Here, the range of the number of OFDM symbolsincluded in the non-slot may be configured with a length of a mini slotup to (normal slot length)−1. Here, although the number of OFDM symbolsmay be limited to 2, 4, or 7 as a non-slot standard, it is provided asan example only.

Also, for example, an SCS corresponding to μ=1 and 2 may be used in theunlicensed band of 6 GHz or less and an SCS corresponding to μ=3 and 4may be used in the unlicensed band above 6 GHz. Here, for example, ifμ=4, it may be used only exclusive for a synchronization signal block(SSB), which is described below. However, it is provided as an exampleonly and the present disclosure is not limited thereto.

Also, Table 2 shows a number N_(slot) ^(symb,μ) of OFDM symbols per slotfor each SCS setting. Table 2 shows a number of OFDM symbols per slotaccording to each SCS value, a number of slots per frame, and a numberof slots per subframe, as provided by Table 1. Here, in Table 2, thevalues are based on the normal slot having 14 OFDM symbols.

TABLE 2 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

Also, as described above, if μ=2 and SCS=60 kHz, the extended CP may beapplied. In Table 3, in the case of the extended CP, each value may beindicated based on the normal slot of which the number of OFDM symbolsper slot N_(slot) ^(symb,μ) is 12. Here, Table 3 shows the number ofsymbols per slot, the number of slots per frame, and the number of slotsper subframe in the case of the extended CP that follows the SCS of 60kHz.

TABLE 3 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)2 12 40 4

Hereinafter, a structure of an SS/Physical Broadcast Channel (PBCH)block in the NR system and an initial cell access structure in the NRsystem are described.

Here, an NR base station (i.e., gNB) may periodically transmit signalsand channels as shown in the following Table 4 to allow an initial cellselection of UEs in a cell.

TABLE 4 SS/PBCH block (i.e., SSB) SIB1 (System Information Block 1)Other SIBs

For example, the SS/PBCH block may be the aforementioned SSB. Here, evenin the NR system, a UE may need to receive a broadcast channel forforwarding a synchronization signal and important system informationtransmitted from a corresponding wireless access system to perform aninitial wireless access. To this end, the UE may check receivingsensitivity of a synchronization signal to discover an optical cellpresent in a most excellent channel environment. The UE may perform afrequency/time synchronization and cell identification operation forperforming an initial access to an optimal channel among one or morechannels in a specific frequency band operated based on the checkedreceiving sensitivity. The UE may verify a boundary of OFDM symboltiming through the aforementioned operation and then may initiate a PBCHdemodulation in the same SSB.

Here, the UE may receive a PBCH demodulation reference signal (DMRS) andmay perform a PBCH demodulation. Also, the UE may acquire 3-leastsignificant bit (LSB) information from SSB index information bitsthrough the PBCH DMRS. The UE may acquire information included in a PBCHpayload by performing the PBCH demodulation. The UE may perform aprocedure of demodulating SIB 1 based on the information acquiredthrough the PBCH.

For example, in the NR system, the UE may receive remaining systeminformation (RMSI) through a broadcast signal or channel as systeminformation not transmitted from the PBCH. Also, the UE may receiveother system information (OSI) and a paging channel through a broadcastsignal or channel as other additional system information.

The UE may access a base station through a random access channel (RACH)process and then perform a mobility management.

Also, for example, when the UE receives an SSB, the UE needs to set anSSB composition and an SS burst set composition.

NR V2X Service

In association with a vehicle-to-everything (V2X) service, the existingV2X service (e.g., LTE Rel-14 V2X) may support a set of basicrequirements for V2X services. Here, the requirements are designedbasically in sufficient consideration of a road safety service.Therefore, V2X UEs may exchange autonomous status information through asidelink and may exchange the information with infrastructure nodesand/or pedestrians.

Meanwhile, in a further evolved service (e.g., LTE Rel-15) as the V2Xservice, new features are introduced by considering a carrieraggregation in a sidelink, a high order modulation, a latency reduction,a transmit (Tx) diversity, and feasibility for sTTI. Coexistence withV2X UEs (the same resource pool) is required based on the aforementioneddescription, and the services are provided based on LTE.

For example, technical features may be classified largely based on fourcategories as represented by the following Table 5 by considering usecases for supporting a new V2X service as system aspect (SA) 1. Here, inTable 5, “Vehicles Platooning” may be technology that enables aplurality of vehicles to dynamically form a group and similarly operate.Also, “Extended Sensors” may be technology that enables exchange of datagathered from sensors or video images. Also, “Advanced Driving” may betechnology that enables a vehicle to drive based on semi-automation orfull-automation. Also, “Remote Driving” may be technology for remotelycontrolling a vehicle and technology for providing an application. Basedthereon, further description related thereto may be given by thefollowing Table 5.

TABLE 5 Vehicles Platooning Vehicles Platooning enables the vehicles todynamically form a platoon travelling together. All the vehicles in theplatoon obtain information from the leading vehicle to manage thisplatoon. This information allows the vehicles to drive closer thannormal in a coordinated manner, going to the same direction andtravelling together. Extended Sensor Extended Sensor enables theexchange of raw or processed data gathered through local sensors or livevideo images among vehicles, road site units, devices of pedestrian andV2X application servers. The vehicles can increase the perception oftheir environment beyond of what their own sensors can detect and have amore broad and holistic view of the local situation. High data rate isone of the key characteristics. Advanced Driving Advanced Drivingenables semi-automated or full-automated driving. Each vehicle and/orRSU shares its own perception data obtained from its local sensors withvehicles in proximity and that allows vehicles to synchronize andcoordinate their trajectories or maneuvers. Each vehicle shares itsdriving intention with vehicles in proximity too. Remote Driving RemoteDriving enables a remote driver or a V2X application to operate a remotevehicle for those passengers who cannot drive by themselves or remotevehicles located in dangerous environments. For a case where variationis limited and routes are predictable, such as public transportation,driving based on cloud computing can be used. High reliability and lowlatency are the main requirements.

Also, the above SA1 may consider all of LTE and NR as enhanced V2X(eV2X) support technology for supporting the new V2X service. Forexample, an NR V2X system may be a first V2X system. Also, an LTE V2Xsystem may be a second V2X system. That is, the NR V2X system and theLTE V2X system may be different V2X systems. In the following,description is made based on a method of satisfying low latency and highreliability required in an NR sidelink based on the NR V2X system. Here,even in the LTE V2X system, the same or similar composition may beexpanded and thereby apply. However, it is provided as an example onlyand the present disclosure is not limited thereto. That is, even in theLTE V2X system, the present disclosure may apply to an interactableportion and is not limited to the following embodiment. Here, forexample, NR V2X capability may not be limited to essentially supportonly V2X services and V2X RaT to be used may be selected.

NR Sidelink

An NR sidelink may be used for the aforementioned NR V2X service. Here,for example, an NR sidelink frequency may consider FR1 that is afrequency of 6 GHz or less and FR2 (i.e., up to 52.6 GHz) that is afrequency over 6 GHz. Also, for example, the NR sidelink frequency mayconsider all of unlicensed ITS bands and licensed ITS bands. That is, asdescribed above, a common design method for supporting the respectivefrequency bands may be required. To this end, an NR sidelink design thatconsiders an NR system may be required. For example, similar to an NRstandard design, although it is not beam-based, even an omni-directionalTx/Rx may basically require the NR sidelink design capable of supportingbeam-based transmission and reception. However, it is provided as anexample only.

Also, for example, a physical channel for NR V2X sidelink may be set.For example, an NR Physical Sidelink Shared Channel (PSSCH) may be adata channel for NR sidelink as a physical channel. Also, for example,an NR Physical Sidelink Control Channel (PSCCH) may be a control channelfor NR sidelink as a physical channel. Here, scheduling information forthe data channel of the NR sidelink and control information may beforwarded through the NR PSCCH. For example, Sidelink ControlInformation (SCI) may be transmitted based on a format that definesfields about control information associated with scheduling of the NRsidelink data channel and control information transmitted through the NRPSCCH may be transmitted based on an SCI format.

Also, for example, an NR Physical Sidelink Feedback Channel (PSFCH) maybe defined. Here, the NR PSFCH may be an NR Hybrid Automatic RepeatRequest (HARQ) feedback channel as a physical channel. Here, HARQ-ACKfeedback information, Channel Status Information (CSI), and otherinformation corresponding to the NR sidelink data channel may beforwarded through the NR PSFCH. In detail, Sidelink Feedback ControlInformation (SFCI) including feedback information may be forwardedthrough the NR PSFCH. Here, SFCI may include information about at leastone of HARQ-ACK, channel quality information (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), reference signal received power(RSRP), reference signal received quality (RSRQ), path-gain/pathloss, ascheduling request indicator (RSI), contention resolution identity(CRI), an interference condition, a vehicle motion, and the like.However, it is provided as an example only and the present disclosure isnot limited thereto. Here, for example, the NR PSFCH is furtherdescribed.

NR V2X QoS Requirements

NR V2X QoS requirements may be a higher level than existing V2X (e.g.,LTE V2X) requirements into consideration of a service of the above Table5. For example, delay may be set within 3 ms to 100 ms based on thefollowing Table 6. Also, reliability may be set between 90% and 99.999%.Also, a data rate may be required up to 1 Gbps.

TABLE 6 Delay: [3, 100 ms] Reliability: [90%, 99.999%] Data rate: up to1 Gbps

That is, as described above, QoS requirements capable of meeting lowlatency and high reliability may be required into consideration of a V2Xservice. Here, for example, access stratum (AS) level QoS management maybe required to meet the QoS requirements. Also, for example, HARQ andCSI may be required into consideration of link adaptation to meet theQoS requirements. Also, for example, maximum bandwidth (max. BW)capability may differ for each NR V2X UE. That is, AS level informationneeds to be exchanged between UEs based on the aforementioneddescription. For example, the AS level information may include at leastone of UE capability, QoS related information, radio bearerconfiguration, and physical layer configuration. Also, for example, theAS level information may further include other information. However, itis provided as an example only and the present disclosure is not limitedthereto.

The following Table 7 may show the respective terms applied herein.However, it is provided as an example only and the present disclosure isnot limited thereto.

TABLE 7 UMTS (Universal Mobile Telecommunications System): refers to 3rdGeneration (3G) mobile communication technology based on Global Systemfor Mobile Communication (GSM), developed by 3GPP EPS (Evolved PacketSystem): refers to a network system that includes an Evolved Packet Core(EPC) that is a packed switched (PS) core network based on an Internetprotocol (IP) and an access network such as LTE/Universal TerrestrialRadio Access Network (UTRAN). A network evolved from Universal MobileTelephone System (UMTS). NodeB: refers to a base station of GERAN/UTRANand is installed outdoors and has coverage of macro cell scale. eNodeB:refers to a base station of E-UTRAN and is installed outdoors and hascoverage of macro cell scale. gNodeB: refers to a base station of NR andis installed outdoors and has coverage of macro cell scale. UE (UserEquipment): refers to a user equipment. The UE may also beinterchangeably used with terms, terminal, mobile equipment (ME), mobilestation (MS), and the like. Also, the UE may be a portable device, suchas a laptop computer, a mobile phone, a personal digital assistant(PDA), a smartphone, a multimedia device, etc. The term “UE” or“terminal” in Machine Type Communications (MTC) related content mayrefer to an MTC device. RAN (Radio Access Network): refers to a unitthat includes NodeB, eNodeB, and gNodeB, and a radio network controller(RNC) for controlling the same in a 3GPP network, and is present betweenUEs and provides a connectivity to a core network. NG-RAN (NextGeneration Radio Access Network): refers to NG-eNB (E-UTRA UP/CPprotocol) and gNB (NR UP/CP protocol) base station nodes connected to5GC (5G Core NW) based on an NG interface in a 3GPP network. Xninterface: refers to an interface for interconnection between NG-eNB andgNB. PLMN (Public Land Mobile Network): refers to a network configuredto provide a mobile communication service to individuals, and may beconfigured for each operator. Proximity service (or ProSe Service orProximity based Service): refers to a service that enables discovery anddirect communication between physically proximate apparatuses,communication through a base station, or communication through a thirdapparatus. Here, user plane data is exchanged through a direct data pathwithout going through a 3GPP core network (e.g., EPC). LTE SFN (SystemFrame Number): refers to a frame index for time domain reference of LTE.NR SFN (System Frame Number): refers to a frame index for time domainreference of NR. NR DFN (Direct Frame Number): refers to a frame indexfor time domain reference of an NR sidelink

NR Sidelink Design

Hereinafter, an NR V2X sidelink design method that meets requirementsfor the aforementioned evolved V2X (i.e., eV2X) services will bedescribed.

In more detail, a synchronization procedure and method required to forma wireless link for an NR sidelink are further described. For example,as described above, in NR sidelink design, FR1 and FR2 (i.e., up to 52.6GHz) may be considered as NR sidelink frequencies and unlicensed ITSbands and licensed ITS bands may be considered as frequency band andrange in which an NR system operates. Also, for example, theavailability of an LTE (NG-eNB)/NR Uu link that is a 3GPP NG-RAN ofTable 7 may be considered in the NR sidelink design.

Also, for example, design fore V2X synchronization informationforwarding and signal transmission/reception to meet higher requirementsfrom the evolved V2X services may be considered. Here, a frequency forNR V2X sidelink communication may further consider at least one ofelements of the following Table 8 based on the following technologiesrequired in the new system, which differs from the existing system(e.g., That is, there is need to meet new V2X service requirements byapplying an NR V2X sidelink based on NR radio access technology,particularly, uplink transmission related technologies as shown in thefollowing Table 8.

Also, other elements may be considered by considering the new system aswell as the following Table 8. However, it is provided as an exampleonly and the present disclosure is not limited thereto.

TABLE 8 Scalable frequency use and configuration (e.g., Bandwidth Part[BWP]) according to broad frequency band and maximum bandwidthcapability of UE Various numerologies (e.g., variable SCSs, number ofOFDM symbols per slot (or subframe)) Slot format (slot/non-slot)Beam-based transmission/reception to cope with signal attenuation in afrequency band of 6 GHz or more corresponding to a high frequency bandConfigured grant-based uplink transmission/reception to provide lowlatencyAlso, as described above, for example, a signal, a basic slot structure,a physical resource, and a physical channel of NR V2X sidelink may berepresented as the following Table 9.

TABLE 9 NR PSSCH (Physical Sidelink Shared Channel) Refers to a Physicallayer NR SL data channel. NR PSCCH (Physical Sidelink Control Channel)Refers to a channel for forwarding control information as well asscheduling information of an NR SL data channel as a physical layer NRSL control channel. NR SLSS/PSBCH (Sidelink SynchronizationSignal/Physical Sidelink Broadcast Channel) block Refers to asynchronization and broadcast channel block in which an NR SLsynchronization signal and a broadcast channel are transmitted on asingle continuous time in a physical layer. Periodical transmission isperformed based on a set of at least one block index to supportbeam-based transmission on an NR frequency band. The synchronizationsignal includes a PSSS and a SSSS and a sequence for the correspondingsignal is generated based on at least one SLSSID value. The PSBCH istransmitted with SLSS for the purpose of forwarding system informationrequired to perform V2X SL communication. Likewise, periodictransmission is performed based on a set of SLSS/PSBCH block indices tosupport beam-based transmission.

Here, for example, FIG. 3 illustrates an example of a basic networkarchitecture composition considered for an NR V2X sidelink.

For example, referring to FIG. 3 , NG interfaces may be set betweennodes 310-1 and 310-2 of a 5-th generation core (5GC NW) and nodes320-1, 320-2, 330-1, and 330-2 of an NG-RAN. Also, Xn interfaces may beset between the nodes 320-1, 320-2, 330-1, and 330-2 of the NG-RAN.Here, in the above architecture, corresponding nodes may beinterconnected through the corresponding Xn interface based on gNB (NRUP/CP protocol) corresponding to the nodes 320-1 and 320-2 and ng-eNB(E-UTRA UP/CP protocol) corresponding to the nodes 330-1 and 330-2,which constitute the NG-RAN. Also, as described above, in the 5GC,corresponding nodes may be interconnected through a corresponding NGinterface. Here, for example, in the above architecture, all of an LTEsidelink UE and an NR sidelink UE may be controlled by the NG-RAN (i.e.,LTE Uu and NR Uu) based on the gNBs and ng-eNBs. Therefore, whentransmitting synchronization information, the NR sidelink UE may receivesynchronization information from the LTE Uu or NR Uu link, and maytransmit NR sidelink synchronization information (e.g., SLsynchronization signal/SL Physical Broadcast Channel (PBCH)) based onthe received synchronization information. However, it is provided as anexample only and the present disclosure is not limited thereto. That is,the NR sidelink UE may also acquire the synchronization informationthrough the LTE Uu link as well as the NR Uu link.

Meanwhile, with respect to V2X sidelink communication, V2X sidelink UEsmay perform the V2X sidelink communication. Here, predeterminedconditions need to be met such that the V2X sidelink UEs may start thecommunication. The conditions may be represented by the following Table10. That is, a V2X sidelink UE may perform V2X sidelink communication ina Radio Resource Control (RRC) idle mode, inactive mode, or connectedmode. Also, V2X sidelink UEs that perform the V2X sidelink communicationneed to be registered on a selected cell on a using frequency or need tobelong to the same PLMN. Also, if a V2X sidelink UE is an OOC on afrequency for V2X sidelink communication, the V2X sidelink UE mayperform the V2X sidelink communication only when it is possible toperform the V2X sidelink communication based on pre-configuration.

TABLE 10 If a UE is in an RRC_IDLE or INACTIVE or CONNECTED mode in aspecific cell, If a UE is registered to a selected cell on a frequencyused for V2X SL communication or belongs to the same PLMN, If a UE is anOCC on a frequency for a V2X SL communication operation, and if a UE iscapable of performing V2X SL communication based on pre-configuration

Here, as described above, to start the V2X sidelink communication,sidelink synchronization information may be required. Therefore, the UEneeds to transmit the sidelink synchronization information. Here, a TxUE (sidelink Tx UE) may receive a configuration for transmittingsidelink synchronization information prior to transmitting correspondingsynchronization information. Here, for example, the Tx UE may receivethe configuration for transmitting the sidelink synchronizationinformation based on a system information message or an RRCreconfiguration message (in the case of an RRC CONNECTED UE) broadcastedfrom the above NG-RAN nodes. Also, for example, if an NR V2X sidelink UE(hereinafter, referred to as a UE) is absent in an NG-RAN, the UE maytransmit sidelink synchronization information based on thepre-configured information, which is described above.

Meanwhile, FIG. 4 illustrates an example of a scenario in which NR V2Xsidelink communication is performed in a 3GPP network based on theaforementioned description. Here, the NR V2X sidelink communication maybe performed on the 3GPP network (hereinafter, NG-RAN). Additionally,presence of a Global Navigation Satellite System (GNSS) signal may beconsidered.

In detail, referring to FIG. 4 , each of NR V2X sidelink UEs may be anIC or an OOC based on EUTRA NG-eNB 410, may also be an IC or an OOCbased on gNB 420, and may also be an IC or an OOC based on GNSS 430.Here, NR V2X sidelink UEs may select a resource of synchronizationreference based on a position and capability of a UE. Also, for example,in addition to the scenario of FIG. 4 , scenarios shown in the followingTable 11 may be considered. It is provided as an example only and thepresent disclosure is not limited thereto.

TABLE 11 NR Uu CONNECTED/IDLE/Inactive for NR Sidelink NG-eNB UuCONNECTED/IDLE for NR Sidelink EN-DC or MR-DC for NR Sidelink

Meanwhile, in the following, an NR SCS may refer to one of an SCS valuefor NR DL SS/PBCH, an SCS value for an NR BWP (data/control channel),and a reference SCS value defined/set for comparison of NR V2X SCSvalues. As another example, the NR SCS may refer to one of an SCS valuefor NR V2X SLSS/PSBCH, an SCS value for NR V2X BWP or a resource pool(data/control channel), and a reference SCS value defined/set forcomparison of NR V2X SCS values. However, it is provided as an exampleonly and the present disclosure is not limited thereto. Also, forexample, 30 kHz SCS value may be set as a default value and used for 5.9GHz ITS spectrum. However, it is provided as an example only and thepresent disclosure is not limited thereto.

In the case of performing NR V2X sidelink communication, datatransmission may be performed based on unicast/groupcast. Here, forexample, unicast transmission may refer to transmitting a message from asingle UE to another UE, that is, one-to-one transmission. Also,broadcast transmission may refer to a scheme of transmitting a messageto all of UEs regardless of whether a service is supported at an Rx UE.That is, a single UE may transmit a message regardless of whether aplurality of Rx UEs is supporting a service. Meanwhile, a groupcasttransmission scheme may be a scheme of transmitting a message to aplurality of UEs that belongs to a group.

Here, for example, whether to activate the unicast, groupcast, orbroadcast data transmission and reception and whether to perform asession connection may be determined at an upper layer. That is,although a physical layer of a V2X UE may operate based on aninstruction that is determined in an upper layer, it is provided as anexample only and the present disclosure is not limited.

Also, for example, a V2X UE may perform corresponding transmission andreception after a session for corresponding unicast or groupcast datatransmission is formed. When a V2X UE performs transmission andreception based on the aforementioned session, physical layer parameterinformation for data transmission corresponding to unicast or groupcastmay be known in advance in the physical layer of the V2X UE. Forexample, the V2X UE may receive and recognize in advance theaforementioned information from a base station. As another example, theaforementioned information may be information preset to the V2X UE.Here, for example, unicast or multicast data transmission and receptionmay apply only to a case in which a relatively small number of V2X UEsare present around a Tx V2X UE and a session is stably maintained. Inaddition, if a session is unstable or if adjacent V2X UEs vary a lot,data transmission may be performed based on broadcast transmission.Here, it is provided as an example only and the present disclosure isnot limited thereto.

Also, for example, as described above, unicast or groupcast transmissionand reception may be determined in an application layer end as an upperlayer. Here, for example, data allocable to transmission and receptiongenerated in an application layer may be not directly mapped to a radiolayer. Here, for example, in the case of performing the unicast orgroupcast transmission and reception, a mapping relationship or aconnection establishment procedure may be required to perform datatransmission and reception on the radio layer. However, it is providedas an example only and the present disclosure is not limited thereto.

Also, for example, in the case of performing the unicast datatransmission and reception, corresponding Tx and Rx UEs may need toestablish a session by performing a procedure (e.g., a discoveryprocedure) of discovering their presence, and such session establishmentmay be performed based on various methods. Here, the sessionestablishment between the UEs may be performed with assistance of a basestation. The base station may gather position information of UEs and maydetermine whether UEs capable of performing unicast or groupcast datatransmission and reception are adjacent to each other. Here, forexample, the base station may determine whether the UEs are adjacent toeach other based on a threshold. Here, a predetermined value may be usedto determine the threshold. When the UEs in a cell are determined to beadjacent to each other, the base station may initialize a correspondingdiscovery procedure and the UEs may perform the corresponding discoveryprocedure to discover each other based on an initialization procedure.Also, the base station may determine whether an adjacent V2X SL UE ispresent by designing a new discovery channel and by periodicallytransmitting and receiving the corresponding channel. Also, the basestation may determine whether an adjacent UE is present by transmittinga corresponding discovery message on a V2X data channel. However, it isprovided as an example only and the present disclosure is not limitedthereto. That is, session establishment for unicast or groupcast datatransmission and reception may be completed based on the aforementionedprocedures. Subsequently, the upper layer may notify the physical layerof information about the session establishment and may perform aphysical layer operation, such as HARQ-ACK, CSI, and link adaptation.

At least some communications (e.g., wireless communication in accordancewith 3GPP 5G NR Release 16, or any earlier or later releases, or anyother wireless communications) may use one or more bandwidth parts(BWPs). For example, for certain transmission and reception of a signal,a frequency bandwidth to be used may not need to be as wide as abandwidth of a serving cell. The bandwidth (e.g., the bandwidth of aBWP) may be configured as a narrower bandwidth than the bandwidth of theserving cell. A frequency position of the bandwidth may be shifted. Abandwidth of an OFDM subcarrier may be changed. It may be defined as apartial set of the entire frequency bandwidth of the serving cell, whichmay be referred to as a BWP or any other terminology.

A serving cell may include one or more BWPs. One or more messages (e.g.,one or more RRC messages) configuring the BWPs of the serving cell mayinclude information about a plurality of different BWPs for a wirelessuser device (e.g., by way of signaling from a base station). The BWPs ofthe serving cell may include a pair of an uplink BWP and a downlink BWP(e.g., at all times). Composition information about a single BWP mayinclude composition information about an uplink and a downlink (e.g., atall times). A number of BWPs to be activated may be limited to a singleBWP among the plurality of BWPs or more than one BWPs may be activatedsimultaneously. If the wireless user device is capable of activating atleast one BWP, the base station may verify information about a maximumnumber of active BWPs of the wireless user device and may alsosimultaneously activate the plurality of BWPs based on the verifiedinformation. For example, if the wireless user device is configured withthe serving cell, a single BWP may be activated for the serving cell(e.g., without separate signaling from the base station). The wirelessuser device may perform access to the serving cell and the wireless userdevice may use the activated BWP (e.g., for an initial access or othertypes or random access). The initial BWP may be used (e.g., until thewireless user device receives composition information for the wirelessuser device from the base station).

If the wireless user device receives the composition information for thewireless user device (e.g., UE composition information) from the basestation, the wireless user device may be configured with a default BWP.The default bandwidth may be configured as a relatively narrow bandwidth(e.g., narrower than other BWPs). If an amount of data to be transmittedand received is small, the wireless user device may reduce batteryconsumption of the wireless user device by activating the defaultbandwidth. If the wireless user device is not configured with thedefault bandwidth, the wireless user device may use the initial BWP forthe same or similar purposes.

The activated BWP of the serving cell may be switched with another BWPdepending on one or more circumstances. This operation may be referredto as BWP switching. For a BWP switching, the wireless user device mayinactivate the currently activated BWP and may activate a new BWP. TheBWP switching operation may be performed, for example, if the wirelessuser device receives BWP switching order (e.g., through a PDCCH order)or any other BWP switching triggering event. The BWP switching operationmay be performed through a predetermined timer “bwp-InactivityTimer” asa timer for BWP inactivity. The BWP switching operation may be performedin response to starting a random access. As further described herein,one or more conditions and/or events that may cause a BWP switching willbe described. The base station may change an active BWP in the servingcell of the wireless user device depending on one or more circumstances.If the wireless user device determines to change an active BWP, the basestation may notify the wireless user device that a BWP is switched. Thenotification of the BWP switching may be indicated through a PDCCH orany other downlink signaling. The wireless user device may perform theBWP switching operation through BWP switching related information (e.g.,included in the PDCCH and/or an RRC configuration).

The timer “BWPInactivityTimer” may be configured for each serving cellor may be commonly used for a plurality of BWPs. “BWPInactivityTimer”may be a timer for inactivating the activated BWP (e.g., if the timerexpires). A timer performing the same functionality may be“BWPInactivityTimer” or any other timers. “BWPInactivityTimer” may beused for clarity of description, other timers or timer parameters mayperform the functions or operations of “BWPInactivityTimer” describedherein. If the timer (e.g., “BWPInactivityTimer”) expires, the wirelessuser device may inactivate the current activate BWP and may activate thedefault BWP. BWP switching may be performed using the default BWP or anyother BWPs. If the wireless user device is not configured with thedefault BWP, the wireless user device may switch to the initial BWP. Thewireless user device may reduce battery consumption by monitoring anarrow bandwidth through the BWP switching operation. Start and restartcondition of the timer may be set (e.g., represented by the followingTable 2). If the wireless user device needs to maintain the activatedBWP as follows, the timer may start or restart to prevent the activatedBWP from being inactivated or from being switched to another BWP. One ormore features of the BWP is further described below.

At least some communications (e.g., wireless communication in accordancewith 3GPP 5G NR Release 16, or any earlier or later releases, or anyother wireless communications) have a wide system bandwidth configurableon a single carrier, which differs from other types of communications,such as LTE. If the NR system (or other communication systems) operatesin frequency range 2 (i.e., over 6 GHz frequency bands) in which manyfrequency bands and bandwidths thereof are available for the NR system,a system bandwidth available for the base station and a bandwidth inwhich the wireless user device actually operates may be differentlyconfigured. The system bandwidth assumed by the base station (or anetwork and/or system) and the frequency bandwidth used for the wirelessuser device to actually operate may conform to 3GPP NR standards (or anyother configurations) and may be different in view of capability ofmaximum RF bandwidth of the base station and the wireless user device,and wireless user device implementations (e.g., UE implementation) andrelated operation. Configurations of the frequency bandwidth used by thewireless user device may be provided from the base station, which maycorrespond to a BWP configuration. The BWP configuration used by thewireless user device may vary based on a mode of the wireless userdevice and a BWP configuration status. In general, bandwidth part (BWP)configuration provided from the base station to the wireless user devicethrough system information for initial cell access may be referred to asan initial active BWP, which may be used to perform a random accessprocedure.

BWPs may include an initial DL BWP. As the BWP provided from the basestation to the wireless user device through system information for theinitial cell access of the wireless user device, a bandwidth about aninitial DL active BWP for System Information Block (SIB1) transmissionand related Control Resource Set (CORESET) configuration information maybe provided through an SS/PBCH block reception. The initial DL activeBWP may be initial UE bandwidth information for receiving SIB1information.

BWPs may include an initial UL BWP. Within the SIB1, configurationinformation for performing a random access procedure may be provided andinformation about an initial uplink bandwidth (e.g., an initial UEuplink bandwidth) for some message transmission/reception within therandom access procedure. For example, initial UL active BWP information(e.g., a frequency position, a bandwidth, numerology, etc.) may beprovided. Through this information, an uplink PUSCH message of a randomaccess procedure (e.g., msg.3 or an uplink RACH message of a four-steprandom access procedure) may be transmitted. Numerology of the initialUL active BWP may be identical to numerology information for msg.3transmission.

PUSCH transmission (e.g., for msg.3) and PUCCH transmission for HARQfeedback transmission (e.g., for msg.4 or a downlink response message ofa four-step random access procedure) within the RACH procedure may belimited to be within the initial active UL BWP.

-   -   In an unpaired spectrum, such as TDD, an initial DL BWP and an        initial UL BWP may share the same center frequency.    -   A bandwidth of the initial active UL BWP may be generally less        than or equal to a minimum Tx bandwidth of the UE.    -   From wireless user device perspective, only a single initial        active UL BWP may be supported per cell-defined SSB.

Once the wireless user device accesses a network through theaforementioned initial cell access procedure, BWP configuration up tomaximum 4 BWPs may be provided to the wireless user device (e.g.,through wireless user device-specific RRC signaling). Only a single BWPamong the plurality of BWPs may be active and used.

The following basic configuration information may be generally includedas the BWP configuration.

-   -   Numerology    -   Frequency location (e.g., center frequency)    -   Bandwidth (e.g., number of PRBs)

PDCCH/PDSCH/PUSCH, a configured grant, an SRS transmission relatedconfiguration, and a beam failure recovery (BFR) configuration may beincluded and thereby provided to the wireless user device.

Numerology and Waveform Supported in NR V2X

Numerology and waveform supported in one or more wireless communications(e.g., NR2V2X or any other wireless communications) may be configured(e.g., represented by the following Table 12). Referring to Table. 12,the numerology for NR V2X may support a normal CP for 15 kHz, 30 kHz,and 60 kHz and an extended CP for 60 kHz for PSCCH/PSSCH and PSFCH inFR1 (e.g., frequency ranges below 6 GHz). The numerology may support anormal CP for 60 kHz and 120 kHz and an extended CP for 60 kHz forPSCCH/PSSCH and PSFCH in FR2 (e.g., frequency ranges equal to or above 6GHz). Also, the waveform for NR V2X may support only CP-OFDM withoutsupporting DFT-S-OFDM.

TABLE 12 FR 1 FR 2 PSSCH/PSCCH and Normal CP for 15 kHz, 30 kHz, 60 kHzNormal CP for 60 kHz, 120 kHz PSFCH Extended CP for 60 kHz Extended CPfor 60 kHz Waveform Supported only CP-OFDM (i.e., No support ofDFT-S-OFDM for NR SL in Rel-16

One or more resource pools may be configured for one or more wirelessuser devices (e.g., by higher layer signaling, such as an RRC message).The one or more resource pools may include one or more NR V2X resourcepools. For example, the NR V2X resource pool may include a set of timeand frequency resources available for sidelink transmission andreception (e.g., for NR V2X communication). The resource pool may be ina radio frequency bandwidth (RF BW). Only a single numerology (onedifferent numerologies) may be used in a single resource pool. Thewireless user device may be configured with at least one pool on asingle carrier. A single resource pool for PSSCH may includediscontinuous time resources, and frequency resources may includecontinuous or discontinuous Physical Resource Blocks (PRBs).

Referring to FIG. 5 , part (a), a resource pool for PSSCH may includediscontinuous time resources in the NR V2X resource pool. If an NR V2Xservice is provided on a licensed carrier on which an NR Uu linkoperates, the wireless user device may be configured with the NR V2Xresource pool through a base station or a pre-configuration in additionto a physical resource for the NR Uu link. Resources 512, 514, and 515for sidelink may be discontinuously configured based on a symbol unit ora slot unit within the NR V2X resource pool. If the sidelink resourcepool is configured on the licensed carrier on which the NR Uu linkoperates, they may be multiplexed on different symbols or slots as shownin FIG. 5 , part (a). A single resource pool for PSSCH may be configuredas discontinuous time resources.

Referring to FIG. 5 , part (b), the resource pool for PSSCH may includecontinuous or discontinuous PRBs in the NR V2X resource pool. For Option1 of FIG. 5 , part (b), each of resource pools 521, 522, and 523 forPSSCH may include continuous PRBs. For Option 2 of FIG. 5 , prat (b),each of resource pools 524, 525, 526, 527, 528, and 529 for PSSCH mayinclude discontinuous PRBs. Resource pool 1 (524 and 527) may beconfigured on discontinuous frequency resources as shown in FIG. 5 ,part (b). The wireless user device may perform sidelink communicationbased on the resource pool, and the operation is further describedbelow.

BWPs may comprise one or more NR V2X sidelink BWPs. The NR V2X sidelinkBWP may be configured on a single sidelink carrier. The correspondingsidelink carrier may be a licensed carrier on which an NR Uu linkoperates or a C-V2X dedicated unlicensed carrier, such as an ITS band.The NR V2X sidelink BWP may be defined independently from an NR Uu BWPwithin the licensed carrier. Only a single NR V2X sidelink BWP (ormultiple NR V2X sidelink BWPs) may be configured on a single carrier.Although the aforementioned numerology configuration may includenumerology configured NR V2X sidelink BWP configuration, aspects are notlimited thereto. The wireless user device may use the NR V2X sidelinkBWP for transmission (Tx) and reception (Rx). The resource pool may beconfigured within a single sidelink BWP. The wireless user device mayassume that an active uplink BWP and a configured sidelink BWP areidentical at a specific point in time of the same carrier. Based on theaforementioned description, the wireless user device may performsidelink communication.

One or more time resources may include one or more time resources forPSFCH. PSFCH time resources may be configured (e.g., by the basestation) per a slot, per two slots, or per 4 slots in the V2X sidelinkresource pool. PSFCH time resources may be pre-configured (e.g., for thewireless user device) per a slot, per two slots, or per 4 slots in theV2X sidelink resource pool. If a wireless user device receives sidelinkdata (e.g., PSSCH), the wireless user device may perform PSFCHtransmission after a minimum time to prepare PSFCH transmission. Theminimum time may be configured by considering a processing time of thewireless user device.

Referring to FIG. 6 , PSFCH time resources may be configured per 4 slotsin the resource pool. The PSFCH may be transmitted per 4 slots (or perany other number of slots). In FIG. 6 , a PSFCH time resource 610 may beconfigured in slot 0 and PSFCH time resources 620 and 630 may beconfigured in slot 4 and slot 8, respectively. Other configurations maybe possible. A wireless user device (e.g., an Rx UE) may transmit HARQfeedback information to another wireless user device (e.g., the Tx UE)through a PSFCH time resource associated with a PSSCH. Referring to FIG.6 , a PSSCH of slot 0, a PSSCH of slot 1, a PSSCH of slot 2, and a PSSCHof slot 3 may be associated with the PSFCH time resource 620 of slot 4.The wireless user device may transmit the PSFCH through a PSFCH timeresource (e.g., the first PSFCH time resource 620 occurring after thesidelink HARQ transmission) after a minimum time gap for sidelink HARQfeedback transmission. In FIG. 6 , the wireless user device may performsidelink HARQ feedback transmission through the PSFCH time resource 620of slot 4 that is a PSFCH time resource occurring after the minimum timegap. If the minimum time gap is large, the wireless user device mayperform the sidelink feedback transmission through the PSFCH timeresource 630 of slot 8, instead of using the PSFCH time resource 620 ofslot 4. However, aspects are not limited thereto.

PSFCH resources may include frequency resources and/or code resources.In addition to time resources for the PSFCH, frequency resources mayneed to be determined. Referring to FIG. 7 , a wireless user device(e.g., Tx UE) may transmit a PSCCH 710 and a PSSCH 720 to anotherwireless user device (e.g., an Rx UE). A frequency resource 730 used totransmit a PSFCH may be implicitly determined based on a frequencyresource used to transmit the PSSCH 720. The frequency resource 730 usedto transmit the PSFCH may be determined based on a starting RB (or astarting subchannel) of the frequency resource used to transmit thePSSCH 720. The frequency resource 730 used to transmit the PSFCH may bedetermined based on a lowest RB index or a lowest subchannel index inthe frequency resource used to transmit the PSSCH 720. However, aspectsare not limited thereto.

A wireless user device may perform a sidelink HARQ procedure. Whether toperform sidelink HARQ feedback may be configured (e.g., by an upperlayer, such as RRC signaling). The sidelink HARQ feedback may bedifferently performed based on a cast scheme. The sidelink HARQ feedbackmay be enabled or disabled based on a configuration (e.g., by the upperlayer) in unicast and groupcast. If a HARQ feedback-enabled wirelessuser device, based on the upper layer configuration, performs a HARQfeedback transmission for a groupcast transmission, it may be determinedwhether the corresponding wireless user device actually performs theHARQ feedback transmission for the groupcast transmission based on achannel status (e.g., RSRS), Tx-Rx distance, QoS requirements, and otherconditions. If sidelink HARQ feedback for unicast is enabled, thewireless user device (e.g., the Rx UE) may transmit HARQ-ACK/NACK toanother wireless user device (e.g., the Tx UE) depending on whether acorresponding transport block (TB) is successfully decoded.

If sidelink HARQ feedback for groupcast is enabled and a conditionregarding the actual HARQ feedback transmission status is satisfied(e.g., a condition about the Tx-Rx distance), the wireless user device(e.g., the Rx UE) may transmit only HARQ NACK to another wireless userdevice (e.g., the Tx UE). If the corresponding TB is not successfullydecoded, the wireless user device (e.g., the Rx UE) may transmit HARQNACK to another wireless user device (e.g., the Tx UE) (Option 1). Ifsidelink HARQ feedback for groupcast is enabled, a wireless user device(e.g., the Rx UE) may transmit HARQ-ACK/NACK to another wireless userdevice (e.g., the Tx UE) depending on whether the corresponding TB issuccessfully decoded (Option 2). For the groupcast, a sidelink HARQfeedback report scheme may be supported in a different manner. If awireless user device (e.g., the Rx UE) reports only HARQ NACK asgroupcast (e.g., Option 1), a wireless user device (e.g., the Rx UE) maydetermine whether to perform reporting by considering a distance fromanother wireless user device (e.g., the Tx UE). If the Tx-Rx distance isless than or equal to a required communication range, a wireless userdevice (e.g., the Rx UE) may transmit the HARQ feedback for PSSCH. Ifthe Tx-Rx distance is greater than the required communication range, awireless user device (e.g., the Rx UE) may not perform the HARQ feedbacktransmission for PSSCH.

For the groupcast, although the HARQ feedback is enabled, a wirelessuser device (e.g., the Rx UE) may not perform HARQ report based on theTx-Rx distance. A position of a wireless user device (e.g., the Tx UE)may be indicated through SCI associated with the PSSCH. A wireless userdevice (e.g., the Rx UE) may calculate the Tx-Rx distance based oninformation included in SCI and its position information and maydetermine whether to perform the HARQ feedback accordingly.

An NR V2X sidelink design that meets requirements for new evolved V2X(i.e., eV2X) services will be described based on the aforementioneddescription. A sidelink HARQ transmission method in which, if a mode 1wireless user device performs NR sidelink unicast transmission, the mode1 wireless user device may transmit sidelink HARQ information to a basestation, which will be further described. An NR sidelink frequency foran NR sidelink operation may be within FR1 (410 MHz˜7.125 GHz) and FR2(24.25 GHz 52.6 GHz) and may apply to all of unlicensed ITS bands andlicensed ITS bands, and a frequency band range in which the NR systemoperates, without being limited to a specific band. The NR sidelinkfrequency may commonly apply to all of the aforementioned FR 1 and FR 2.The availability of an LTE (ng-eNB)/NR (gNB) Uu link (e.g., configuredin a 3GPP NG-RAN) may be considered for NR V2X sidelinktransmission/reception procedures. By considering the aforementionedaspects, ng-eNB or gNB on the NG-RAN may be described as the basestation. However, aspects are not limited to a specific type.

A wireless user device may repot sidelink HARQ (e.g., V2X SL HARQ) to abase station. A wireless user device (e.g., an NR V2X Tx UE) configuredwith a base station scheduling mode (i.e., mode 1) may be scheduled witha sidelink transmission resource through the base station. The mode 1wireless user device may request the base station for a transmissionresource to transmit V2X service-related data to another wireless userdevice through a sidelink. in response to the request from the wirelessuser device, the base station may schedule the sidelink transmissionresource and provide the scheduled resource to the wireless user device.The wireless user device may perform a V2X sidelink transmission usingthe scheduled resource.

A wireless user device (e.g., the V2X Tx UE) configured with a wirelessuser device auto-control mode (i.e., mode 2) may autonomously select asidelink transmission resource and may transmit data to another wirelessuser device through the selected resource. The wireless user device maybe pre-configured with a transmission resource pool to be used by thewireless user device (e.g., the V2X Tx UE). The wireless user device mayautonomously select a portion of resources to be used for actual V2Xdata transmission from among resources within the transmission resourcepool.

A wireless user device (e.g., the V2X Tx UE) may acquire SL HARQ-ACKfeedback information about the PSSCH (data channel) transmitted toanother wireless user device (e.g., the V2X Rx UE) through the sidelink,from the other wireless user device (e.g., the Rx UE) through PSFCH. Ifthe wireless user device (e.g., the Tx UE) is in a base stationscheduling mode, the wireless user device (e.g., the Tx UE) may transmitcorresponding sidelink HARQ-ACK feedback information to the base station(e.g., through an NR Uu link) to inform the base station regardingwhether to perform retransmission scheduling. The wireless user device(e.g., the Tx UE) may transmit the corresponding sidelink HARQ-ACKfeedback information to the base station (e.g., using an NR Uu uplinkchannel). The wireless user device (e.g., the Tx UE) may multiplex andthereby transmit CSI (e.g., HARQ-ACK, CQI, PMI, RI, etc.) on the NR Uulink and the sidelink HARQ feedback information through the uplinkchannel. The wireless user device (e.g., the Tx UE) may transmit onlythe corresponding sidelink HARQ-ACK feedback information to the basestation through the uplink channel. However, aspects are not limitedthereto.

Referring to FIG. 8 , a wireless user device (e.g., an NR V2X Tx UE 810)corresponding to a source wireless user device may transmit a PSSCH(i.e., data) to another wireless user device (e.g., an NR V2X Rx UE 820)corresponding to a destination wireless user device through a sidelink.The wireless user device (e.g., NR V2X Tx UE 810) may receive HARQ-ACKfeedback information from another wireless user device (e.g., the NR V2XRx UE 820). If the wireless user device (e.g., the NR V2X Tx UE 810) isa mode 1 configured wireless user device and the sidelink transmissionis performed based on unicast, the wireless user device (e.g., the NRV2X Tx UE 810) may report to a base station 830 for sidelink HARQ-ACKfeedback information received from the other wireless user device (e.g.,the NR V2X Rx UE 820) through an NR Uu uplink channel. The wireless userdevice (e.g., the NR V2X Tx UE 810) may need to determine an uplinkchannel transmission timing of the NR Uu link associated with thesidelink HARQ-ACK feedback information received from the other wirelessuser device (e.g., the NR V2X Rx UE 820). Hereinafter, a method ofconfiguring a transmission timing is described.

An uplink channel transmission timing of an NR Uu link associated withsidelink HARQ-ACK feedback information may be determined based onsidelink downlink control information (SL DCI) and ACK/NACK window (A/Nwindow).

A wireless user device (e.g., a Tx UE) configured with mode 1 mayreceive sidelink data scheduling related information and controlinformation from a base station for sidelink unicast data transmission.The base station may transmit SL related control information to thewireless user device (e.g., the Tx UE) through a PDCCH based on an SLDCI format. The SL DCI format may include Uu HARQ timing indicationinformation associated with SL HARQ (SL HARQ (PSFCH) to Uu HARQ timingindication). The wireless user device (e.g., the Tx UE) may be aware ofa Uu HARQ timing associated with SL HARQ through the SL DCI. The basestation may configure, to the wireless user device (e.g., the Tx UE),A/N window information about Uu HARQ timing indication informationassociated with SL HARQ (e.g., through RRC signaling) for Uu HARQ timingindication information associated with SL HARQ. The wireless user device(e.g., the Tx UE) may be aware of an uplink channel transmission timingof an NR Uu link associated with SL HARQ-ACK feedback information basedon A/N window information configured through RRC and Uu HARQ timinginformation associated with SL HARQ acquired through the SL DCI.

The A/N window may not correspond to a sidelink resource pool but maycorrespond to an uplink resource of a Uu link. The A/N window may beconfigured and apply only in an uplink slot. The A/N window, as a movingwindow, may be used with a length corresponding to a length of theconfigured window after a relatively minimum preparation time in aspecific PSFCH reception slot.

The A/N window may be configured based on a physical slot or a symbolindex regardless of sidelink resources or NR Uu link resources. If theA/N window is configured based on the physical slot or the symbol indexregardless of sidelink resources or NR Uu link resources, the wirelessuser device (e.g., the Tx UE) may transmit SL HARQ feedback informationto the base station through the NR Uu link in an uplink slot and/orsymbol based on A/N window configuration information and/or signaling.

Referring to FIG. 9 , a wireless user device (e.g., a Tx UE) maytransmit each of PSSCHs 921, 922, 923, and 924 to another wireless userdevice (e.g., the Rx UE) in a corresponding slot based on eachcorresponding SL DCI 911, 912, 913, 914, respectively. A PSFCH resourcemay be implicitly indicated based on a PSSCH, and may be configured, asa time resource, per a single slot, two slots, or 4 slots, etc. Afrequency resource may be configured based on a starting RB/subchannelof a PSSCH. Although the following configuration is described based on acase in which a PSFCH resource is configured per a slot, aspects are notlimited thereto (e.g., a PSFCH resource may be configured per N slots,where N is an integer). One or more configurations described herein mayapply regardless of whether PSFCH resources are configured per two slotsor 4 slots.

The wireless user device (e.g., the Tx UE) may receive a PSFCH in thesame slot 0 corresponding to the PSSCH1 (slot 0) 921. The wireless userdevice (e.g., the Tx UE) may transmit sidelink HARQ feedback informationreceived from the corresponding PSFCH to a base station through anuplink channel of a Uu channel. The start of possible sidelink A/Nwindow that enables the transmission of the sidelink HARQ feedback tothe base station through the uplink channel may be determined byconsidering a minimum processing time and the like. The A/N window maystart from a first uplink slot/symbol in which the uplink channel can betransmitted after considering the minimum processing time and otherlatencies. A size of the A/N window may be differently configured. Thesize of the A/N window may be configured by the base station and may beindicated to the wireless user device (e.g., to the Tx UE through RRC).If the size of the A/N window is 4, the A/N window may be configured infour slots (e.g., slots 4 to 7 as shown in FIG. 9 ). If the size of theA/N window is 8, the A/N window may be configured in eight slots (e.g.,slots 4 to 7 and slots 10 to 13 as shown in FIG. 9 ). The A/N window maybe configured using uplink resources of the Uu link instead of using asidelink resource pool. If the size of the A/N window is configured, thewireless user device (e.g., the Tx UE) may transmit sidelink HARQinformation received within the A/N window to the base station. A slotfor transmitting the sidelink HARQ information received within the A/Nwindow may be indicated through corresponding SL DCI.

Sidelink HARQ information about the PSSCH1 921 transmitted from thewireless user device (e.g., the Tx UE) in the slot 0 may be received inthe slot 0 through the PSFCH. The A/N window for the PSSCH1 921 may beconfigured from the slot 4 by considering the last OFDM symbol of aPSFCH reception slot, a minimum processing time, and other latencies.The received sidelink HARQ information about the PSSCH1 921 may betransmitted in the slot 4 within the A/N window. A slot for transmittingthe received sidelink HARQ information about the PSSCH1 921 may beindicated through the corresponding SL DCI, for example, the SL DCI1911. Sidelink HARQ information about the PSSCH2 922 transmitted from thewireless user device (e.g., the Tx UE) in the slot 1 may be received inthe slot 1. The A/N window for the PSSCH2 922 may be configured from theslot 4 by considering a minimum processing time and other latencies. Thereceived sidelink HARQ information about the PSSCH2 922 may betransmitted in the slot 4 within the A/N window through the PSFCH. Aslot for transmitting the received sidelink HARQ information about thePSSCH2 922 may be indicated through corresponding SL DCI, for example,the SL DCI2 912. Sidelink HARQ information about PSSCH3 923 transmittedfrom the wireless user device (e.g., the Tx UE) in slot 2 may bereceived in slot 2 through the PSFCH. The A/N window for the PSSCH3 923may be configured from the slot 4 by considering a minimum processingtime and other latencies. The received sidelink HARQ information aboutthe PSSCH3 923 may be transmitted in the slot 4 within the A/N windowthrough the PSFCH. A slot for transmitting the received sidelink HARQinformation about the PSSCH3 923 may be indicated through thecorresponding SL DCI, for example, the SL DCI3 913.

Sidelink HARQ information about the PSSCH4 924 transmitted from thewireless user device (e.g., the Tx UE) in the slot 4 may be received inthe slot 4 through the PSFCH. The A/N window for the PSSCH4 924 may beconfigured from the slot 5 by considering a minimum processing time andother latencies from a PSFCH reception slot/OFDM symbol including HARQinformation. A first slot after the minimum processing time and theother latencies may be the slot 5. For the sidelink HARQ information,the A/N window for the PSSCH4 924 may be configured from the slot 5. Ifa size of the A/N window is 8, the A/N window may be configured usingslots 5 to 7 and slots 10 to 14. The received sidelink HARQ informationabout the PSSCH4 924 may be transmitted in the slot 6 within the A/Nwindow. A slot for transmitting the received sidelink HARQ informationabout the PSSCH4 924 may be indicated through corresponding SL DCI, forexample, the SL DCI4 914.

A starting point of the A/N window may be determined by considering aprocessing time (e.g., a time used for PSFCH demodulation andPUCCH/PUSCH transmission preparation) of the wireless user device fromthe last OFDM symbol of a slot in which the PSFCH is received, a Tx/Rxswitching (e.g., SL<->UL) time, an AGC time, and other latencies. Theaforementioned time may be a minimum preparation time. The minimumpreparation time may be pre-configured or may be configured by the basestation. However, aspects are not limited thereto. A single piece ofsidelink HARQ information may be transmitted to the base station throughthe uplink channel by a length of the A/N window from an NR uplink slot(e.g., a sidelink A/N transmittable slot) identical to or earlier thanthe configured minimum preparation time. NR uplink slot candidates inwhich SL HARQ can be transmitted may be determined based on at least oneof a PSFCH reception slot index, the minimum preparation time, and A/Nwindow configuration. The corresponding A/N window may operate as themoving window. The A/N window may be continuous or discontinues based onconfiguration. If the A/N window is configured to be continuous, thebase station may configure A/N window starting point and lengthinformation for the wireless user device (e.g., the Tx UE). If the A/Nwindow is configured to be discontinuous, the base station may configurean A/N window starting point and a relative offset value for thewireless user device (e.g., the Tx UE). The base station may indicate adiscontinuous slot. If the A/N window is configured with “{0 (startingslot), 1 (offset), 3 (offset), 7 (offset), 9 (offset)}”, the startingslot and slots corresponding to the relative offset may be A/N Txcandidate slots. The offset value may be applied by counting only a ULslot from a starting uplink slot.

The 0 zero value configured among the A/N window configuration valuesmay indicate that a PUCCH transmission and a PSFCH reception areperformed in the same slot. The PSFCH reception and the PUCCHtransmission may be performed in the same slot.

The sidelink A/N window may be determined using a number of physicalslots regardless of downlink/uplink and sidelink, for example, based onthe PSFCH reception slot. Unlike one or more examples above, thesidelink A/N window may be determined using a number of physical layersbased on the PSFCH reception slot. A downlink slot or a sidelink slot(but not an uplink slot) may be included in the A/N window. The basestation may indicate transmission of the sidelink A/N through the uplinkslot instead of using the downlink slot and the sidelink slot within theA/N window. SL DCI may indicate a slot for the sidelink A/N transmissionas the uplink slot in the A/N window.

A Uu HARQ timing associated with sidelink HARQ report may be indicatedthrough SL DCI, which is described above. Table 13 shows an example of aUu HARQ timing information field configuration associated with sidelinkHARQ within an SL DCI format. A number of bits of a correspondinginformation field within SL DCI may be determined based on a length ofthe A/N window configured by the base station or a number of Uu HARQtiming values associated with sidelink HARQ. The range of Uu HARQ timingvalues associated with the sidelink HARQ may be the range of valuesconfigured in the A/N window. Without the aforementioned configuration,a Uu HARQ timing value associated with sidelink HARQ may be possiblewithin the predetermined range of values. The predetermined range ofvalues may be used as {1, 2, 3, . . . , 8}. If a Uu HARQ timing valueassociated with sidelink HARQ is configured (e.g., by RRC signaling),the Uu HARQ timing value associated with the sidelink HARQ may have thewider range. One of 1, 2, and 3 bits in Table 13 may be used in the SLDCI format based on a number of slots (e.g., a number of slotscorresponding to an SL HARQ to Uu HARQ timing) within the correspondingpredetermined range of values or the range of values configured by RRCsignaling. The wireless user device (e.g., the Tx UE) may determine anNR uplink channel transmission timing based on a PSFCH slot in which atiming value indicated by a Uu HARQ timing indication field associatedwith sidelink HARQ of SL DCI is received from another wireless userdevice (e.g., the Rx UE).

A specific uplink transmission timing within the A/N window may beconfigured (e.g., by A/N RRC signaling) or may be performed based on apre-configured value. However, aspects are not limited thereto. If theaforementioned A/N window configuration information is not provided tothe wireless user device, the wireless user device (e.g., the TX UE) mayuse the pre-configured A/N window configuration as a default value. Thedefault value may include {1, 2, 3, 4, 5, 6, 7, 8} or another basicvalue may be configured.

TABLE 13 PSFCH-to-HARQ_feedback timing indicator NR Uu slots SL_k 1 bit2 bits 3 bits within a A/N window 0 00 000 1^(st) value provided bySL-HARQToUL-ACK 1 01 001 2^(nd) value provided by SL-HARQToUL-ACK 10 0103^(rd) value provided by SL-HARQToUL-ACK 11 011 4^(th) value provided bySL-HARQToUL-ACK 100 5^(th) value provided by SL-HARQToUL-ACK 101 6^(th)value provided by SL-HARQToUL-ACK 110 7^(th) value provided bySL-HARQToUL-ACK 111 8^(th) value provided by SL-HARQToUL-ACK

If the wireless user device (e.g., the Tx UE) performs sidelink datatransmission based on Sidelink Semi-Persistent Scheduling (SL SPS)and/or if the wireless user device (e.g., the Tx UE) performs sidelinkdata transmission configured through RRC signaling, a Uu HARQ timingassociated with sidelink HARQ may be determined as described above.

If sidelink transmission is performed based on SL SPS, scheduling may beperformed based on SL SPS activation. The wireless user device (e.g.,the Tx UE) may activate SL SPS based on an SL DCI format indicating theSL SPS activation. The wireless user device (e.g., the Tx UE) mayperform the sidelink transmission through pre-configured resources basedon the SL SPS. The Uu HARQ timing associated with sidelink HARQ may alsoapply even if the sidelink transmission is performed based on the SLSPS. The base station may include information indicating the Uu HARQtiming associated with sidelink HARQ in the SL DCI format activating theSL SPS transmission and may transmit the same to the mode 1 wirelessuser device (e.g., mode 1 Tx UE) through a PDCCH. The Uu HARQ timingassociated with sidelink HARQ may be determined in the aforementionedmanner. An uplink slot timing for transmitting sidelink A/N informationabout a sidelink PSSCH SPS transmission may be indicated through atiming indication field (e.g., “SL A/N to Uu A/N timing indication”information field) within SL DCI indicating SL SPC activation. An uplinkslot for sidelink A/N transmission for associated sidelink PSSCH SPStransmission may be determined based on A/N window configuration andindication information within SL DCI for SL SPS activation within theA/N window.

Referring to FIG. 10 , SL DCI1 1011 may be SL DCI for activating SL SPS.A PSSCH1 1021, a PSSCH2 1022, and a PSSCH3 1023 may be scheduled in anSPS form based on the SL DCI1 1011. A/N window configuration may beindicated through RRC signaling by the base station. A Uu HARQ timingassociated with sidelink HARQ may be determined by a Uu HARQ timingindication associated with the sidelink HARQ included in DCI (e.g., SLDCI1 1011) indicating SL SPS activation. Although a size of the A/Nwindow may be configured as 4 in FIG. 10 , aspects are not limitedthereto. The size of the A/N window may be differently configured and/ordetermined. The SL DCI1 1011 indicating the SL SPS activation mayinstruct/cause the wireless user device (e.g., the Tx UE) to report tothe base station for sidelink HARQ feedback about the PSSCH1 1021 andsidelink HARQ feedback about the PSSCH2 1022 in a first slot (e.g., slot4 1031) of the A/N window. The wireless user device (e.g., the Tx UE)may transmit, to the base station, the sidelink HARQ feedback about thePSSCH1 1021 and the sidelink HARQ feedback about the PSSCH2 1022 throughan uplink channel of a Uu link in the first slot of the A/N window. TheSL DCI1 1011 may instruct/cause the wireless user device (e.g., the TxUE) to report to the base station for sidelink HARQ feedback about thePSSCH3 1023 through a first slot (e.g., slot 10 1032) within the A/Nwindow after a slot (e.g., a PSFCH reception slot) in which the sidelinkHARQ feedback about the PSSCH3 1023 is received. The wireless userdevice (e.g., the Tx UE) may transmit the sidelink HARQ feedback aboutthe PSSCH3 1023 to the base station through the uplink channel of the Uulink in the first slot (e.g., slot 10 1032) of the A/N window.

The base station may indicate semi-static PSSCH/PSCCH transmissionresources of the wireless user device (e.g., the mode 1 Tx UE) throughRRC signaling. The base station may not indicate a Uu HARQ timingassociated with sidelink HARQ to the wireless user device (e.g., the TxUE) through SL DCI and may configure the wireless user device (e.g., theTx UE) to perform Uu HARQ transmission associated with sidelink HARQ ina specific slot within the A/N window through RRC signaling. The basestation may instruct/cause the wireless user device (e.g., the Tx UE) totransmit associated sidelink HARQ feedback information in the leftmostslot within the A/N window. Here, the Tx UE may transmit the receivedsidelink HARQ feedback information to the base station through an uplinkchannel.

FIG. 11 illustrates an example method for performing Uu HARQtransmission associated with sidelink HARQ. Referring to FIG. 11 , abase station 1110 may transmit, to the wireless user device (e.g., a TXUE 1120), information required to transmit sidelink HARQ feedbackinformation to a base station through RRC signaling. The wireless userdevice (e.g., the Tx UE 1120) may verify the information required totransmit sidelink HARQ feedback information to a base station through apre-configuration. The information required to transmit sidelink HARQfeedback information to a base station may include at least one of: A/Nwindow configuration information, configuration information for sidelinkA/N timing indicator field composition within an SL DCI format, and/orPSFCH transmission/reception related configuration information. Thewireless user device (e.g., the Tx UE 1120) may monitor a CORESET todetermine whether a PDCCH (SL DCI format) including schedulinginformation for sidelink data transmission (e.g., unicast/groupcasttransmission) through a downlink is received from the base station 1110.If the wireless user device (e.g., the Tx UE 1120) detects the PDCCHtransmission including the SL DCI format from a downlink slot, thewireless user device (e.g., the Tx UE 1120) may receive PSSCH/PSCCHscheduling information for sidelink data transmission from the SL DCIformat. The wireless user device (e.g., the Tx UE 1120) may receive,through the SL DCI format, PUCCH resource indicator information andsidelink HARQ-associated Uu HARQ transmission timing (e.g., SL-to-Uu A/NTx timing (=PSFCH-to-HARQ_feedback timing indicator)) information forreporting to the base station 1110 for sidelink HARQ feedbackinformation received from another wireless user device (e.g., the Rx UE1130). If the PSSCH is scheduled based on SL SPS, the wireless userdevice (e.g., the Tx UE 1120) may receive PUCCH resource indicatorinformation and sidelink HARQ-associated Uu HARQ transmission timing(e.g., SL-to-Uu A/N Tx timing (=PSFCH-to-HARQ_feedback timingindicator)) information through a PDCCH activating SL SPS scheduling(e.g., SL DCI for SL SPS activation). If PSSCH scheduling is configuredbased on RRC signaling, the wireless user device (e.g., the Tx UE 1120)may configure PUCCH resource indicator information and sidelinkHARQ-associated Uu HARQ transmission timing (e.g., SL-to-Uu A/N Txtiming (=PSFCH-to-HARQ_feedback timing indicator) information throughRRC signaling. If PSSCH scheduling is configured based on RRC signaling,the wireless user device (e.g., the Tx UE 1120) may pre-configure PUCCHresource indicator information and sidelink HARQ-associated Uu HARQtransmission timing (SL-to-Uu A/N Tx timing (=PSFCH-to-HARQ_feedbacktiming indicator) information.

The wireless user device (e.g., the Tx UE 1120) may transmit thePSSCH/PSCCH to another wireless user device (e.g., the Rx UE 1130). Thewireless user device (e.g., the Tx UE 1120) may receive sidelink HARQfeedback information from the other wireless user device (e.g., the RxUE 1130) through the PSFCH if a specific time elapses. The wireless userdevice (e.g., the Tx UE 1120) may transmit sidelink HARQ feedbackinformation received from the other wireless user device (e.g., the RxUE 1130) via the PSFCH mapped on an uplink channel (e.g., PUCCH orPUSCH), for example, based on an uplink transmission timing indicated byat least one of SL DCI and/or RRC signaling.

Sidelink HARQ feedback information about at least one PSSCH may bemultiplexed through the same uplink transmission slot and the sameuplink channel. A plurality of pieces of sidelink HARQ feedbackinformation may be multiplexed through the same uplink channel in thesame slot. PUCCH transmission resources for transmitting the multiplexedplurality of pieces of sidelink HARQ feedback information may bedetermined based on a corresponding SL DCI (e.g., recently receivedsidelink DCI). The PUCCH transmission resources may be determined basedon the corresponding SL DCI (e.g., most recent received SL DCI) among aplurality of SL DCI (PDCCH) transmissions for scheduling-associatedPSSCH. If a PUCCH transmission resource indicator is absent within SLDCI, a PUCCH transmission resource (e.g., frequency/code resource index)for sidelink HARQ feedback transmission may be configured through RRCsignaling. If the PUCCH transmission resource indicator not included inSL DCI, the PUCCH transmission resource (e.g., frequency/code resourceindex) for sidelink HARQ feedback transmission may be determined by apre-configuration.

Sidelink V2X may be configured to operate in a plurality of servingcells (multiple carriers). The wireless user device (e.g., the Tx UE1120) may transmit data to another wireless user device (e.g., the Rx UE1130) through sidelink using the plurality of serving cells. SidelinkHARQ feedback information may be required per the plurality of servingcells or per each of the plurality of serving cells. If all of aplurality of pieces of sidelink HARQ feedback information aremultiplexed on the same uplink serving cell, slot, and uplink channelbased on SL DCI that schedules sidelink V2X data transmission on theplurality of serving cells, a PUCCH transmission resource may bedetermined based on SL DCI corresponding to a largest serving cell indexin a most recently received SL DCI slot (e.g., in NR V2X carrieraggregation). If PUCCH transmission resource indicator information isnot included in SL DCI, the PUCCH transmission resource for HARQfeedback transmission may be determined through RRC signaling or apre-configuration.

Referring to FIG. 12 , if a wireless user device (e.g., a Tx UE)configured with mode 1 performs sidelink transmission based on unicast,the wireless user device (e.g., the Tx UE) may report to a base stationfor sidelink HARQ feedback received from another wireless user device(e.g., an Rx UE). The wireless user device (e.g., the Tx UE) may receivean A/N window configuration from abase station through RRC signaling(S1210). The wireless user device (e.g., the Tx UE) may receive A/Nwindow configuration information from the base station through RRCsignaling. The A/N window may be a candidate resource in which Uu HARQfeedback associated with sidelink HARQ feedback can be transmitted. Asize of the A/N window may be differently configured. The A/N window maybe a window movable by considering a minimum processing time and otherlatencies. The wireless user device (e.g., the Tx UE) may receive SL DCIfrom the base station (S1220). The SL DCI may include informationindicating a Uu HARQ feedback transmission timing associated withsidelink HARQ feedback. If the PSSCH is scheduled based on SL SPS, theUu HARQ feedback transmission timing associated with sidelink HARQfeedback may be indicated by the SL DCI, which is described above. Thewireless user device (e.g., the Tx UE) may perform Uu HARQ feedbacktransmission associated with sidelink HARQ feedback based on atransmission timing indicated by SL DCI within the A/N window. Thewireless user device (e.g., the Tx UE) may transmit the PSCCH/PSSCH toanother wireless user device (e.g., the Rx UE) (S1230) and may receivePSFCH (sidelink HARQ feedback) in response to the transmittedPSCCH/PSSCH (S1240). The wireless user device (e.g., the Tx UE) mayreport to the base station for the sidelink HARQ feedback received fromanother wireless user device (e.g., the Rx UE) (S1250). The wirelessuser device (e.g., the Tx UE) may report sidelink HARQ feedback to thebase station based on the timing indicated within the A/N window, whichis described above.

The wireless user device (e.g., the Tx UE) may directly determine a UuHARQ feedback transmission timing associated with sidelink HARQ feedbackbased on quality of service (QoS) of sidelink data and the A/N window.The wireless user device (e.g., the Tx UE) may receive sidelink HARQfeedback information from another wireless user device (e.g., the RxUE). The wireless user device (e.g., the Tx UE) may directly determine aslot timing for reporting to the base station for sidelink HARQ feedbackinformation received through PSFCH demodulation. The wireless userdevice (e.g., the Tx UE) may directly determine the Uu HARQ feedbacktransmission timing associated with sidelink HARQ feedback byconsidering at least one of QoS information of data corresponding to thesidelink HARQ feedback information, the configured A/N window, and aminimum processing time. If the wireless user device (e.g., the Tx UE)reports to the base station for sidelink HARQ feedback corresponding tohigh QoS sidelink data transmission through an uplink channel of a Uulink, the wireless user device (e.g., the Tx UE) may select a slot valuecorresponding to an earliest PUCCH transmission timing between RRCsignaling and the pre-configured A/N window, and based thereon, thewireless user device (e.g., the Tx UE) may perform Uu HARQ feedbacktransmission associated with sidelink HARQ feedback. The A/N window maybe a PUCCH transmission window. Although the A/N window is used as aterm for clarity of description, a PUCCH transmission window or anyother terminology may be used to describe the A/N window. The A/N windowmay indicate a set of PUCCH transmission timing values and may bereferred to as another name, without being limited to the aforementionedterminologies. Although the A/N window may be determined as one ofvalues 1 to 8 based on a slot unit, it may be determined as othervalues. If the wireless user device (e.g., the Tx UE) reports to thebase station for sidelink HARQ feedback corresponding to low QoSsidelink data transmission through the uplink channel of the Uu link,the wireless user device (e.g., the Tx UE), the wireless user device(e.g., the Tx UE) may select a value corresponding to a latetransmission timing from among timing values within the A/N window. Thewireless user device (e.g., the Tx UE) may perform Uu HARQ feedbacktransmission associated with sidelink HARQ feedback based on theselected transmission timing. A PUCCH transmission slot may be set on aresource configured with an NR uplink slot/OFDM symbol.

Referring to FIG. 13 , a wireless user device (e.g., a Tx UE) mayreceive SL DCI 1311, 1312, 1313, and 1314 for sidelink transmission froma base station. The wireless user device (e.g., the Tx UE) may transmitPSSCHs 1321, 1322, 1323, and 1324 in slots corresponding to the SL DCI1311, 1312, 1313, and 1314, respectively, and may receive sidelink HARQfeedback in response thereto. The wireless user device (e.g., the Tx UE)may be a wireless user device configured with mode 1 and may performsidelink communication based on unicast. The wireless user device (e.g.,the Tx UE) may receive an A/N window configuration from the base stationthrough RRC signaling. The A/N window may be identical to the PUCCHtransmission window.

The PSSCH1 1321 and the PSSCH2 1322 may be low QoS required data. ThePSSCH3 1323 and the PSSCH4 1324 may be high QoS required data. Thewireless user device (e.g., the Tx UE) may receive, from anotherwireless user device (e.g., the Rx UE), sidelink HARQ feedbackinformation about each of PSSCHs 1321, 1322, 1323, and 1324 through aPSFCH. The wireless user device (e.g., the Tx UE) may report to the basestation for each piece of sidelink HARQ feedback information receivedfrom the other wireless user device (e.g., the Rx UE). The wireless userdevice (e.g., the Tx UE) may transmit sidelink HARQ feedback informationabout the PSSCH3 1323 requiring high QoS in a first slot (e.g., slot 41331) within the A/N window. The wireless user device (e.g., the Tx UE)may transmit sidelink HARQ feedback information about the PSSCH4 1324requiring high QoS in the first slot (e.g., slot 4 1331) within the A/Nwindow. The wireless user device (e.g., the Tx UE) may directlydetermine a slot for transmitting sidelink HARQ feedback information.The wireless user device (e.g., the Tx UE) may select an earliest slotwithin the A/N window, for example, because corresponding data requireshigh QoS and the wireless user device may report the sidelink HARQfeedback information to the base station, and accordingly, may provide alow latency service.

The wireless user device (e.g., the Tx UE) may transmit sidelink HARQfeedback information about the PSSCH1 1321 requiring low QoS in a thirdslot (e.g., slot 6 1332) within the A/N window. The wireless user device(e.g., the Tx UE) may transmit sidelink HARQ feedback information aboutthe PSSCH2 1322 requiring low QoS in the third slot (e.g., slot 6 1332)within the A/N window. The wireless user device (e.g., the Tx UE) maydirectly determine a slot for transmitting sidelink HARQ feedbackinformation. Because corresponding data requires low QoS, the wirelessuser device (e.g., the Tx UE) may select an arbitrary slot from the A/Nwindow and may report the sidelink HARQ feedback information to the basestation.

In association with the aforementioned operation, the wireless userdevice (e.g., the Tx UE) may determine a HARQ transmission timing of Uuassociated with sidelink HARQ feedback, for example, by referring to thefollowing Table 14 to Table 16. Table 14 shows PQI (PC5 5QI (5G QoSIdentifier)) and QoS mapping information (Standardized PQI to QoScharacteristics mapping). “Resource Type”, “Default Priority Level”,“Packet Delay Budget”, “Packet Error Rate”, “Default Maximum Data BurstVolume”, and “Default Averaging Window” corresponding to PQI may bemapped based on QoS parameter information of NR V2X. A “PUCCH (SL A/N)Tx timing” value may be additionally mapped to PQI information as uplinktransmission timing values for sidelink HARQ feedback. A set of PQI andUu HARQ transmission timing values associated with sidelink HARQfeedback may be mapped based on Table 14. The wireless user device(e.g., the Tx UE) may have the aforementioned values and, based thereon,the wireless user device (e.g., the TX UE) may determine a Uu HARQtiming corresponding to sidelink HARQ. Referring to Table 15, a Uu HARQtiming corresponding to sidelink HARQ may be determined based on adefault A/N window. Among PQI values of Table 14, PQI values “55, 82,83” may have top priority, PQI values “1, 56, 57” may have subsequentpriority, and remaining PQI values may have bottom priority. Forexample, if the A/N window (or PUCCH transmission window) is configuredwith 1 to 8, Uu HARQ corresponding to sidelink HARQ may be transmittedthrough “{1, 2, 3}” such that the PQI values “55, 82, 83” having the toppriority may be initially transmitted. With respect to the PQI values“1, 56, 57” having the subsequent priority, Uu HARQ corresponding tosidelink HARQ may be transmitted through “{3, 4, 5}”. With respect tothe other PQI values, Uu HARQ corresponding to sidelink HARQ may betransmitted through a last part “{6, 7, 8}” of the A/N window (or PUCCHtransmission window). Table 16 shows an A/N window configured throughRRC. For example, if the A/N window is configured through RRC, an A/Nwindow value may be configured with 8 or more, which is described above.The aforementioned timing values within the PUCCH transmission window orthe A/N window may be values considering only an NR uplink slot. Forexample, timing values within the A/N window may represent a physicalslot. However, aspects are not limited thereto. For example, a timingindicating a transmission slot of the NR uplink channel for transmittingsidelink HARQ information may be indicated by counting only an NR ULslot.

TABLE 14 Default Default Packet Packet Maximum Default PQI ResourcePriority Delay Error Data Burst Averaging Value Type Level Budget RateVolume Window Example Services 1 GBR 3 20 ms 10−4 N/A 2000 ms Platooningbetween (NOTE 1) UEs - Higher degree of automation; Platooning betweenUE and RSU - Higher degree of automation 2 4 50 ms 10⁻² N/A 2000 msSensor sharing - higher degree of automation 3 3 100 ms 10⁻⁴ N/A 2000 msInformation sharing for automated driving - between UEs or UE and RSU -higher degree of automation 55 Non-GBR 3 10 ms 10⁻⁴ N/A N/A Cooperativelane change - higher degree of automation 56 6 20 ms 10−1 N/A N/APlatooning informative exchange - low degree of automation; Platooning -information sharing with RSU 57 5 25 ms 10−1 N/A N/A Cooperative lanechange - lower degree of automation 58 4 100 ms 10−2 N/A N/A Sensorinformation sharing - lower degree of automation 59 6 500 ms 10⁻¹ N/AN/A Platooning - reporting to an RSU 82 Delay 3 10 ms 10⁻⁴ 2000 bytes2000 ms Cooperative collision Critical avoidance; GBR Sensor sharing -(NOTE 1) Higher degree of automation; Video sharing - higher degree ofautomation 83 2 3 ms 10⁻⁵ 2000 byte 2000 ms Emergency trajectoryalignment; Sensor sharing - Higher degree of automation (NOTE 1): GBRand Delay Critical GBR PQIs can only be used for unicast PC5communications. GBR and Delay Critical GBR can also be used forbroadcast and groupcast.

TABLE 15 PQI Value SL HARQ to Uu HARQ timing value 55, 82, 83 {1, 2, 3}1, 56, 57, {3, 4, 5} Others {6, 7, 8}

TABLE 16 PQI Value SL HARQ to Uu HARQ timing value 55, 82, 83 {0, 1, 2,3} 1, 56, 57, {3, 4, 5, 6, 7, 8} others {8, 9, 10, 11, 12, 13, 14, 15}

If the wireless user device (e.g., the Tx UE) reports sidelink HARQfeedback to the base station at a point in time selected within the A/Nwindow based on the aforementioned description, the base station may beunaware of accurate QoS information about sidelink data at acorresponding point in time. If the wireless user device (e.g., the TxUE) determines a corresponding PUCCH transmission timing, performancereliability of an NR V2X service may be improved. For example, the basestation may perform demodulation by blind-monitoring uplink channelresources for transmitting corresponding sidelink HARQ information basedon a known A/N window configuration. If the size of the A/N windowincreases, the base station may need to attempt more blind demodulation.To reduce burden of blind demodulation of the base station, the size ofthe corresponding A/N window may be adjusted. For example, the A/Nwindow may start from a slot in which the PSFCH is received or from asubsequent slot thereof. The A/N window may end by a slot correspondingto the size of the A/N window. The A/N window may be a moving window.The A/N window may apply from a subsequent slot following a slot (orfrom the slot in which the PSFCH is received). If 0 is included amongtiming values within the A/N window, the value 0 may indicate that aPSFCH slot is identical to a PUCCH slot. The corresponding slot mayindicate that transmission and reception is performed on different OFDMsymbols and the availability thereof may be determined based on aprocessing time and capability of the wireless user device. If thewireless user device (e.g., the Tx UE) determines an NR PUCCH channeltransmission timing for sidelink HARQ transmission on an NR uplink, thewireless user device (e.g., the Tx UE) may select one of values withinthe A/N window by additionally considering a processing time of thewireless user device (e.g., the Tx UE) and numerology, and the like.

FIG. 14 illustrates an example method for performing Uu HARQtransmission associated with sidelink HARQ. Referring to FIG. 14 , abase station 1410 may transmit, to a wireless user device (e.g., a Tx UE1420), information required to transmit sidelink HARQ feedbackinformation to a base station (e.g., through RRC signaling). Thewireless user device (e.g., the Tx UE 1420) may verify the informationrequired to transmit sidelink HARQ feedback information to a basestation (e.g., through a pre-configuration). The information required totransmit sidelink HARQ feedback information to a base station mayinclude at least one of: A/N window configuration information,configuration information for sidelink A/N timing indicator fieldcomposition within an SL DCI format, and PSFCH transmission/receptionrelated configuration information. The wireless user device (e.g., theTx UE 1420) may monitor whether a PDCCH (SL DCI format) includingscheduling information for sidelink data transmission (e.g.,unicast/groupcast transmission) through a downlink is received from thebase station 1410. If the wireless user device (e.g., the Tx UE 1420)detects the PDCCH transmission including the SL DCI format from adownlink slot, the wireless user device (e.g., the Tx UE 1420) mayreceive PSSCH/PSCCH scheduling information for sidelink datatransmission from the SL DCI format. The wireless user device (e.g., theTx UE 1420) may receive PUCCH resource indicator information through theSL DCI format or through RRC/pre-configuration. If the PSSCH isscheduled based on SL SPS, the wireless user device (e.g., the Tx UE1420) may receive PUCCH resource indicator information through the PDCCHactivating SL SPS scheduling (SL DCI for SL SPS activation). If PSSCHscheduling is configured based on RRC signaling, the wireless userdevice (e.g., the Tx UE 1420) may configure PUCCH resource indicatorinformation through RRC signaling. If PSSCH scheduling is configuredbased on RRC signaling, the wireless user device (e.g., the Tx UE 1420)may pre-configure PUCCH resource indicator information.

The wireless user device (e.g., the Tx UE 1420) may transmit thePSSCH/PSCCH to another wireless user device (e.g., the Rx UE 1430). Thewireless user device (e.g., the Tx UE 1420) may receive sidelink HARQfeedback information from the other wireless user device (e.g., the RxUE 1430) through the PSFCH if a specific time elapses. The wireless userdevice (e.g., the Tx UE 1420) may autonomously determine a Uu HARQfeedback transmission timing associated with sidelink HARQ feedbackbased on QoS information of data transmitted through the PSSCHassociated with the corresponding sidelink feedback transmission. Thewireless user device (e.g., the Tx UE 1420) may determine the Uu HARQfeedback transmission timing associated with sidelink HARQ feedbackwithin an A/N window configuration and may transmit the same through anUL channel (e.g., PUCCH or PUSCH) in the determined UL slot.

Sidelink HARQ feedback information about at least one PSSCH may bemultiplexed through the same uplink transmission slot and the sameuplink channel. A plurality of pieces of sidelink HARQ feedbackinformation may be multiplexed through the same uplink channel in thesame slot. PUCCH transmission resources for transmitting the multiplexedplurality of pieces of sidelink HARQ feedback information may bedetermined based on the most recently received sidelink DCI. The PUCCHtransmission resources may be determined based on the most recentlyreceived SL DCI among a plurality of pieces of SL DCI (PDCCH)transmissions for scheduling-associated PSSCH. If a PUCCH transmissionresource indicator is not included in SL DCI, a PUCCH transmissionresources (e.g., frequency/code resource index) for sidelink HARQfeedback transmission may be configured through RRC signaling. If thePUCCH transmission resource indicator is not included in the SL DCI, thePUCCH transmission resources (e.g., frequency/code resource index) forsidelink HARQ feedback transmission may be determined through apre-configuration.

Sidelink V2X may be configured to operate in a plurality of servingcells (multiple carriers). The wireless user device (e.g., the Tx UE1420) may transmit data to another wireless user device (e.g., the Rx UE1430) through the sidelink using the plurality of serving cells.Sidelink HARQ feedback information may be required per the plurality ofserving cells. If all of a plurality of pieces of sidelink HARQ feedbackinformation are multiplexed on the same uplink serving cell, slot, anduplink channel based on SL DCI that schedules sidelink V2X datatransmission on the plurality of serving cells, a PUCCH transmissionresource may be determined based on SL DCI corresponding to a largestserving cell index in the most recently received SL DCI slot (e.g., NRV2X carrier aggregation). If PUCCH transmission resource indicatorinformation is not included in SL DCI, the PUCCH transmission resourcefor HARQ feedback transmission may be determined through RRC signalingor a pre-configuration.

Referring to FIG. 15 , if a Tx UE configured with mode 1 performssidelink transmission based on unicast, the wireless user device (e.g.,the Tx UE) may report to the base station for sidelink HARQ feedbackreceived from another wireless user device (e.g., an Rx UE). Thewireless user device (e.g., the Tx UE) may receive A/N windowconfiguration from a base station through RRC signaling (S1510). Thewireless user device (e.g., the Tx UE) may receive A/N windowconfiguration information from the base station through RRC signaling.The A/N window may be a candidate resource in which Uu HARQ feedbackassociated with sidelink HARQ feedback can be transmitted. A size of theA/N window may be differently configured. The A/N window may be a windowmovable by considering a minimum processing time and other latencies.The wireless user device (e.g., the Tx UE) may receive SL DCI from thebase station (S1520). The wireless user device (e.g., the Tx UE) mayreceive scheduling information of the PSSCH/PSCCH for sidelink datatransmission from the SL DCI format. The wireless user device (e.g., theTx UE) may receive PUCCH resource indicator information through the SLDCI format. If the PSSCH is scheduled based on SL SPS, the wireless userdevice (e.g., the Tx UE) may receive PUCCH resource indicatorinformation through the PDCCH activating SL SPS scheduling (e.g., SL DCIfor SL SPS activation). If PSSCH scheduling is configured based on RRCsignaling, the wireless user device (e.g., the Tx UE) may configurePUCCH resource indicator information through RRC signaling. If PSSCHscheduling is configured based on RRC signaling, the wireless userdevice (e.g., the Tx UE) may pre-configure PUCCH resource indicatorinformation.

The wireless user device (e.g., the Tx UE) may transmit the PSCCH/PSSCHto another wireless user device (e.g., the Rx UE) (S1530), and, inresponse thereto, the wireless user device (e.g., the Tx UE) may receivePSFCH (sidelink HARQ feedback) (S1540). The wireless user device (e.g.,the Tx UE) may directly determine a timing for reporting to the basestation about the sidelink HARQ feedback received from the otherwireless user device (e.g., the Rx UE) (S1550). The wireless user device(e.g., the Tx UE) may report the sidelink HARQ feedback to the basestation based on the timing directly determined within the A/N window(S1560).

A Uu HARQ feedback transmission timing associated with sidelink HARQfeedback may be semi-statically determined. The Uu HARQ feedbacktransmission timing associated with sidelink HARQ feedback may bedetermined based on RRC signaling. The base station may define a PSFCHoccasion associated with a single uplink slot and may configure relatedinformation for the wireless user device (e.g., the Tx UE). The basestation may configure information for the wireless user device (e.g.,the Tx UE).

Referring to FIG. 16 , a wireless user device (e.g., a Tx UE) mayreceive each of SL DCI 1611, 1612, 1613, and 1614 and may transmit therespective corresponding PSSCHs 1621, 1622, 1623, and 1624 to anotherwireless user device (e.g., an Rx UE). A PSFCH occasion and a timing forUu HARQ feedback transmission may be associated with each other. Slot 01621 and slot 1 1622 may be associated with slot 4 1631. The wirelessuser device (e.g., the Tx UE) may report to a base station for sidelinkHARQ feedback about the PSSCH1 (slot 0) 1621 and the PSSCH2 (slot 1)1622 in the slot 4 1631. Slot 1 1622 and slot 2 1623 may be associatedwith slot 5 1632. The wireless user device (e.g., the Tx UE) may reportto the base station for sidelink HARQ feedback about the PSSCH2 (slot 1)1622 and the PSSCH3 (slot 2) 1623 in the slot 5 1632. Slot 2 1623 andslot 3 1624 may be associated with slot 6 1633. The wireless user device(e.g., the Tx UE) may report to the base station for sidelink HARQfeedback about the PSSCH3 (slot 2) 1623 and the PSSCH4 (slot 3) 1624 inthe slot 6 1633.

The relationship between the PSFCH occasion and the uplink slot may besemi-statically pre-configured or may be configured through base stationRRC signaling. The wireless user device (e.g., the Tx UE) may determinea number of sidelink HARQ bits and an uplink slot in which the sidelinkHARQ bits are to be transmitted based on the configuration. If acorresponding PSFCH occasion is configured through RRC signaling peruplink slot, RRC parameters may be configured (e.g., as shown in thefollowing Table 17). Continuous/discontinuous sidelink slot index or anumber of PSFCH slots may be indicated starting from an initial PSFCHoccasion per each radio frame as a related PSFCH occasion per an uplinkslot (PUCCH/PUSCH).

A configuration parameter (e.g., UL slot index) for a single uplink slotor a plurality of uplink slots associated with the PSFCH occasion may beconfigured.

TABLE 17 PSFCH occasion per a UL slot (PUCCH/PUSCH): Continuous ordiscontinuous PSFCH occasion (SL slot index or number of PSFCH slots)starting from initial PSFCH occasion per radio frame Configurationparameter (UL slot index) for a single UL slot or a plurality of ULslots associated with the PSFCH occasion

If a Uu HARQ feedback transmission timing is semi-statically determined,the wireless user device (e.g., the Tx UE) may receive at least one of:PSFCH transmission/reception related configuration information and PSFCHoccasion configuration information per uplink slot required to transmitsidelink HARQ feedback information to the base station through RRCsignaling or a pre-configuration. The A/N window may not be configured(e.g., in the above case) and a specific uplink slot for the PSFCHoccasion may be determined.

The wireless user device (e.g., the Tx UE) may monitor a PDCCH (SL DCIformat) including scheduling information for sidelink data transmission(e.g., unicast/groupcast transmission). If the wireless user device(e.g., the Tx UE) detects the PDCCH transmission including the SL DCIformat from downlink slots, the wireless user device (e.g., the Tx UE)may receive PUCCH resource indicator information as well as PSSCH/PSCCHscheduling information for sidelink data transmission from thecorresponding SL DCI format. The PUCCH resource indicator may beconfigured based on RRC/pre-configuration. If PSSCH scheduling is for SLSPS, the wireless user device (e.g., the Tx UE) may receive theaforementioned information through the PDCCH activating SL SPSscheduling (e.g., SL DCI for SL SPS activation).

If PSSCH scheduling is configured based on RRC signaling, at least oneof: PSFCH occasion configuration information per uplink slot and PSFCHtransmission/reception related configuration information as well asPSSCH/PSCCH scheduling information may be configured based on RRCsignaling or pre-configuration information. The wireless user device(e.g., the Tx UE) may receive sidelink HARQ feedback information fromanother wireless user device (e.g., the Rx UE) through the PSFCH if aspecific time elapses after transmitting the PSSCH/PSCCH. The wirelessuser device (e.g., the Tx UE) may transmit sidelink HARQ feedbackinformation received from the other wireless user device (e.g., the RxUE) through the uplink channel (e.g., PUCCH or PUSCH) in an uplink slotcorresponding to an uplink transmission timing that is determined basedon PSFCH occasion configuration information per uplink slot.

Sidelink HARQ feedback information about at least one PSSCH may bemultiplexed through the same uplink transmission slot and the sameuplink channel. A plurality of pieces of sidelink HARQ feedbackinformation may be multiplexed through the same uplink channel in thesame slot. A PUCCH transmission resource for transmitting themultiplexed plurality of pieces of sidelink HARQ feedback informationmay be determined based on the most recently received sidelink DCI. ThePUCCH transmission resource may be determined based on the most recentlyreceived SL DCI among a plurality of SL DCI (PDCCH) transmissions forscheduling associated at least one PSSCH. If a PUCCH transmissionresource indicator is not included in SL DCI, a PUCCH transmissionresource (e.g., frequency/code resource index) for sidelink HARQfeedback transmission may be configured through RRC signaling. If thePUCCH transmission resource indicator is not included in SL DCI, thePUCCH transmission resource (e.g., frequency/code resource index) forthe sidelink HARQ feedback transmission may be determined by apre-configuration.

Sidelink V2X may be configured to operate in a plurality of servingcells (multiple carriers). The wireless user device (e.g., the Tx UE)may transmit data to another wireless user device (e.g., the Rx UE)through the sidelink using the plurality of serving cells. Sidelink HARQfeedback information may be required per the plurality of serving cells.If all of the plurality of pieces of sidelink HARQ feedback informationare multiplexed on the same uplink serving cell, slot, and uplinkchannel based on SL DCI that schedules sidelink V2X data transmission onthe plurality of serving cells, a PUCCH transmission resource may bedetermined based on SL DCI corresponding to a largest serving cell indexin the most recently received SL DCI slot (e.g., NR V2X carrieraggregation). If PUCCH transmission resource indicator information isnot included in SL DCI, the PUCCH transmission resource for HARQfeedback transmission may be determined through RRC signaling or apre-configuration.

Referring to FIG. 17 , if a wireless user device (e.g., a Tx UE)configured with mode 1 performs sidelink transmission based on unicastand HARQ feedback configuration is enabled, the wireless user device(e.g., the Tx UE) may report to a base station for sidelink HARQfeedback from another wireless user device (e.g., an Rx UE). Thewireless user device (e.g., the Tx UE) may receive configuration of oneor more uplink slots associated with a PSFCH occasion from the basestation through RRC signaling (S1710). The wireless user device (e.g.,the Tx UE) may receive information about the above information of Table17 through RRC signaling. The wireless user device (e.g., the Tx UE) mayreceive SL DCI from a base station (S1720). The wireless user device(e.g., the Tx UE) may receive PSSCH/PSCCH scheduling information forsidelink data transmission from an SL DCI format. The wireless userdevice (e.g., the Tx UE) may receive PUCCH resource indicatorinformation through the SL DCI format. If PSSCH is scheduled based on SLSPS, the wireless user device (e.g., the Tx UE) may receive PUCCHresource indicator information through the PDCCH activating SL SPSscheduling (e.g., SL DCI for SL SPS activation). If PSSCH scheduling isconfigured based on RRC signaling, the wireless user device (e.g., theTx UE) may configure PUCCH resource indicator information through RRCsignaling. If PSSCH scheduling is configured based on RRC signaling, thewireless user device (e.g., the Tx UE) may pre-configure PUCCH resourceindicator information.

The wireless user device (e.g., the Tx UE) may transmit the PSCCH/PSSCHto another wireless user device (e.g., the Rx UE) (S1730), and, inresponse thereto, the wireless user device (e.g., the Tx UE) may receivea PSFCH (sidelink HARQ feedback) (S1740). The wireless user device(e.g., the Tx UE) may determine an uplink timing for reporting to thebase station for the sidelink HARQ feedback received from the otherwireless user device (e.g., the Rx UE) based on PSFCH occasionconfiguration information per uplink slot (S1750). The wireless userdevice (e.g., the Tx UE) may report to the base station for Uu HARQfeedback associated with the sidelink HARQ feedback through an uplinkslot associated with a slot in which the PSFCH is received based on anPSFCH occasion. The wireless user device (e.g., the Tx UE) may reportsidelink HARQ feedback to the base station based on the determineduplink timing (S1760).

PUCCH frequency/code resource configuration for sidelink HARQ feedbacktransmission may be provided by the base station. The wireless userdevice (e.g., the Tx UE) may be configured with the PUCCH frequency/coderesource configuration based on at least one of RRC signaling and SLDCI. An NR PUCCH resource for configured sidelink HARQ informationtransmission may be configured independently from a “PUCCH resource” forUu HARQ transmission corresponding to a PDSCH. If only sidelink HARQinformation bits are included in NR PUCCH transmission, the wirelessuser device (e.g., the Tx UE) may report to the base station forsidelink HARQ information using the independently configured NR PUCCHresource for the sidelink HARQ transmission.

If the size of the A/N window is determined in TDD, the A/N window maynot consider a downlink slot and/or OFDM symbol. The A/N window may beconfigured by considering the uplink slot and/or the OFDM symbol. Thewireless user device (e.g., the Tx UE) may transmit sidelink HARQfeedback to the base station using only the uplink slot and/or the OFDMsymbol. The A/N window may consider only resources associated with theuplink slot and/or the OFDM symbol. The A/N window may not considerresources corresponding to a sidelink slot and/or an OFDM symbol as wellas a downlink slot and/or an OFDM symbol after a slot in which the A/Nwindow starts and may consider only the uplink slot and/or OFDM symbol.

FIG. 18 illustrates a base station device and a terminal device (e.g., awireless user device). Referring to FIG. 18 , a base station device 1800may include a processor 1820, an antenna device 1812, a transceiver1814, and a memory 1816.

The processor 1820 may perform baseband-related signal processing andmay include an upper layer processing 1830 and a physical (PHY) layerprocessing 1840. The upper layer processing 1830 may process anoperation of a Medium Access Control (MAC) layer, a Radio ResourceControl (RRC) layer, or more upper layers. The PHY layer processing 1840may process an operation (e.g., uplink received signal processing anddownlink transmission signal processing) of a PHY layer. The processor1820 may perform the overall operation of the base station device 1800in addition to performing baseband-related signal processing.

The antenna device 1812 may include at least one PHY antenna. If theantenna device 1812 includes a plurality of antennas, Multiple InputMultiple Output (MIMO) transmission and reception may be supported. Thetransceiver 1814 may include a radio frequency (RF) transmitter and anRF receiver. The memory 1816 may include operation processed informationof the processor 1820, software associated with an operation of the basestation device 1800, an operating system (OS), an application, etc., andmay include a component, for example, a buffer.

The processor 1820 of the base station device 1800 may be configured toimplement an operation of a base station described herein.

The terminal device 1850 may include a processor 1870, an antenna device1862, a transceiver 1864, and a memory 1866. Communication with theterminal devices 1850 may be performed based on sidelink communicationbetween multiple terminal devices. Each terminal device 1850 performingsidelink communication may refer to a device that performs sidelinkcommunication with another terminal device 1850 in addition to the basestation device 1800.

The processor 1870 may perform baseband-related signal processing andmay include an upper layer processing 1880 and a PHY layer processing1890. The upper layer processing 1880 may process an operation of a MAClayer, an RRC layer, or more upper layers. The PHY layer processing 1890may process an operation (e.g., downlink received signal processing anduplink transmission signal processing) of a PHY layer. The processor1870 may control the overall operation of the terminal device 1850 inaddition to performing baseband-related signal processing.

The antenna device 1862 may include at least one PHY antenna. If theantenna device 1862 includes a plurality of antennas, MIMO transmissionand reception may be supported. The transceiver 1864 may include an RFtransmitter and an RF receiver. The memory 1866 may store operationprocessed information of the processor 1870, software associated with anoperation of the terminal device 1850, an OS, an application, etc., andmay include a component, for example, a buffer.

The processor 1870 of the terminal device 1850 may be configured toimplement an operation of a wireless user device described herein.

The processor 1820 of the base station device 1800 may configureinformation required to transmit sidelink HARQ feedback information to abase station, for example, for the terminal device 1850 through RRCsignaling. The processor 1820 of the base station device 1800 mayconfigure an A/N window for the terminal device 1850 (e.g., UE) throughRRC signaling. The processor 1820 of the base station device 1800 mayindicate configuration information for sidelink A/N timing indicatorfield configuration within an SL DCI format through RRC signaling. Theprocessor 1820 of the base station device 1800 may indicateconfiguration information associated with PSFCH transmission/receptionthrough RRC signaling.

The processor 1820 of the base station device 1800 may indicate one or aplurality of uplink slot configuration information associated with aPSFCH occasion to the terminal device 1850 (e.g., UE). Information shownin Table 17 may be communicated between the base station device 1800 andthe terminal device 1850. The processor 1820 of the base station device1800 may transmit SL DCI to the terminal device 1850 (e.g., UE). The SLDCI may include uplink timing information to transmit sidelink HARQfeedback information to the base station device 1800. Uplink timinginformation used to transmit sidelink HARQ feedback information may beconfigured within the A/N window. The processor 1820 of the base stationdevice 1800 may transmit SL DCI indicating SLS activation to theterminal device 1850 (e.g., UE). DCI indicating SLS activation mayinclude uplink timing information used to transmit sidelink HARQfeedback information to the base station device 1800. The uplink timinginformation used to transmit sidelink HARQ feedback information may beconfigured within the A/N window. SL DCI may include informationassociated with PSSCH/PSCCH scheduling transmitted from the terminaldevice 1850 (e.g., UE) to another terminal device 1850 (e.g., anotherUE) through a sidelink communication, which is described above.

In addition to the feature described above, the base station and thewireless user device may implement one or more features describedhereinafter. The base station may transmit, to a first wireless userdevice, one or more radio resource control (RRC) signals indicating oneor more parameters associated with sidelink communication betweenwireless user devices. The base station may transmit, to the firstwireless user device, sidelink downlink control information (SL DCI)comprising a first indicator field that indicates a sidelink hybridautomatic repeat request (HARQ) feedback timing. A bitwidth of the firstindicator field may be based on at least one of the one or moreparameters. The first wireless user device may transmit, based on the SLDCI and to a second wireless user device, a first sidelink signal (e.g.a PSSCH and/or a PSCCH). The first wireless user device may receive,during a first time interval and from the second wireless user device,first sidelink HARQ feedback information responsive to the firstsidelink signal. The first wireless user device may determine, based onthe sidelink HARQ feedback timing and based on the first time interval,a second time interval. The first wireless user device may transmit,during the second time interval and to the base station, the firstsidelink HARQ feedback information.

The value of the first indicator field may indicate a timing offsetbetween the first time interval and the second time interval. The one ormore parameters may indicate information of a time window that comprisesthe second time interval. The time window may be configured for thefirst wireless user device to transmit sidelink HARQ feedbackinformation to the base station. The time window may comprise aplurality of discontinuous time intervals, and each of the plurality ofdiscontinuous time intervals may correspond to one or more uplink slots.The first wireless user device may determine, based on the bitwidth andbased on the SL DCI, a value of the first indicator field. The firstwireless user device may determine, based on the value of the firstindicator field, the sidelink HARQ feedback timing. The bitwidth maycorrespond to 1, 2, or 3. The one or more parameters may indicate one ormore timing offset values associated with available timing offsetsbetween the first time interval and the second time interval. Thebitwidth may be determined based on a quantity of the one or more timingoffset values. The first wireless user device may transmit the firstsidelink signal via a PSSCH or a PSCCH. The first time interval maycorrespond to a physical sidelink feedback channel (PSFCH) receptionslot. The second time interval may correspond to an uplink slot or aslot comprising one or more uplink symbols. The first wireless userdevice may receive, from the base station, second SL DCI comprising asecond indicator field that indicates a second sidelink HARQ feedbacktiming. The first wireless user device may transmit, based on the secondSL DCI, a second sidelink signal to a second wireless user device or athird wireless user device. The first wireless user device may receive,during a third time interval, second sidelink HARQ feedback informationresponsive to the second sidelink signal. The first wireless user devicemay determine, based on the second sidelink HARQ feedback timing andbased on the third time interval, the second time interval to transmitthe second sidelink HARQ feedback information. The first wireless userdevice may transmit, during the second time interval and to the basestation, the second sidelink HARQ feedback information. The firstsidelink HARQ feedback information and the second sidelink HARQ feedbackinformation may be multiplexed. The first indicator field may indicate aphysical sidelink feedback channel (PSFCH) to physical HARQ timing. Theone or more parameters may indicate a size of a time window fortransmitting sidelink HARQ feedback information to the base station. TheSL DCI may indicate a slot, in the time window, for transmitting thefirst sidelink HARQ feedback information to the base station. The firstwireless user device may determine, based on the first indicator fieldindicating a first value, that the first time interval and the secondtime interval are in a same slot.

The base station may transmit, to a first wireless user device, one ormore parameters associated with sidelink communication between wirelessuser devices (e.g., information about the time window, etc.). The basestation may transmit, to the first wireless user device, sidelinkdownlink control information (SL DCI) comprising a first indicator fieldthat indicates a sidelink hybrid automatic repeat request (HARQ)feedback timing. After receiving the SL DCI, the first wireless userdevice may transmit, to a second wireless user device, a first sidelinksignal via a physical sidelink shared channel (PSSCH). The firstwireless user device may receive, during a first time interval and fromthe second wireless user device, first sidelink HARQ feedbackinformation responsive to the first sidelink signal. The first wirelessuser device may determine, based on the sidelink HARQ feedback timingand based on the reception of the first sidelink HARQ feedbackinformation, a second time interval. The first wireless user device maytransmit, during the second time interval and to the base station, thefirst sidelink HARQ feedback information. The first wireless user devicemay receive the one or more parameters comprises receiving one or moreradio resource control (RRC) signals indicating the one or moreparameters. A bitwidth of the first indicator field may be based on atleast one of the one or more parameters. The first wireless user devicemay determine the second time interval is based on the first timeinterval. The first wireless user device may determine, based on atleast one of the one or more parameters, a bitwidth of the firstindicator field. The first wireless user device may determine, based onthe SL DCI and the determined bitwidth of the first indicator field, avalue of the first indicator field. The value of the first indicatorfield may be associated with a quantity of slots between a first slotcomprising the first time interval and a second slot comprising thesecond time interval. The first wireless user device may receive, fromthe base station, one or more radio resource control (RRC) signalsindicating at least one of: one or more semi-static sidelinktransmission resources; and/or a slot of a time window for transmittingsidelink HARQ feedback information to the base station. The SL DCI maycomprise a physical uplink control channel (PUCCH) resource indicatorfield indicating one or more uplink resources for transmitting the firstsidelink HARQ feedback information to the base station. The one or moreparameters may indicate one or more timing offset values associated withavailable timing offsets between the first time interval and the secondtime interval. A bitwidth of the first indicator field may be determinedbased on a quantity of the one or more timing offset values.

This disclosure is provided to enable any person skilled in the art topractice the various aspects described herein. Various modifications tothese aspects will be readily apparent to those skilled in the art, andthe generic principles defined herein may be applied to other aspects.Thus, the claims are not intended to be limited to the aspects literallydescribed herein, but are to be accorded the full scope consistent withthe language of the claims. All structural and functional equivalents tothe elements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims.

What is claimed is:
 1. A method comprising: receiving, by a wirelessuser device from a base station, one or more radio resource control(RRC) signals indicating one or more parameters associated with sidelinkcommunication between wireless user devices; receiving, from the basestation, sidelink downlink control information (SL DCI) comprising afirst indicator field that indicates a sidelink hybrid automatic repeatrequest (HARQ) feedback timing, wherein a bitwidth of the firstindicator field is based on at least one of the one or more parameters;based on the SL DCI, transmitting, to a second wireless user device, afirst sidelink signal; during a first time interval, receiving, from thesecond wireless user device, first sidelink HARQ feedback informationresponsive to the first sidelink signal; determining, based on thesidelink HARQ feedback timing and based on the first time interval, asecond time interval, wherein the one or more parameters indicatesinformation of a time window that comprises the second time interval,wherein the time window comprises a plurality of discontinuous timeintervals, and wherein each of the plurality of discontinuous timeintervals corresponds to one or more uplink slots; and during the secondtime interval, transmitting, to the base station, the first sidelinkHARQ feedback information.
 2. The method of claim 1, wherein a value ofthe first indicator field indicates a timing offset between the firsttime interval and the second time interval.
 3. The method of claim 1,wherein the time window is configured for the wireless user device totransmit sidelink HARQ feedback information to the base station.
 4. Themethod of claim 1, further comprising: determining, based on thebitwidth and based on the SL DCI, a value of the first indicator field,wherein determining the sidelink HARQ feedback timing comprisesdetermining, based on the value of the first indicator field, thesidelink HARQ feedback timing.
 5. The method of claim 1, wherein thebitwidth corresponds to 1, 2, or
 3. 6. The method of claim 1, whereinthe one or more parameters indicate one or more timing offset valuesassociated with available timing offsets between the first time intervaland the second time interval, and wherein the bitwidth is determinedbased on a quantity of the one or more timing offset values.
 7. Themethod of claim 1, wherein: transmitting the first sidelink signalcomprises transmitting the first sidelink signal via a physical sidelinkshared channel (PSSCH); the first time interval corresponds to aphysical sidelink feedback channel (PSFCH) reception slot; and thesecond time interval corresponds to an uplink slot or a slot comprisingone or more uplink symbols.
 8. The method of claim 1, furthercomprising: receiving, from the base station, second SL DCI comprising asecond indicator field that indicates a second sidelink HARQ feedbacktiming; based on the second SL DCI, transmitting, to a second wirelessuser device or a third wireless user device, a second sidelink signal;during a third time interval, receiving second sidelink HARQ feedbackinformation responsive to the second sidelink signal; determining, basedon the second sidelink HARQ feedback timing and based on the third timeinterval, the second time interval to transmit the second sidelink HARQfeedback information; and during the second time interval, transmitting,to the base station, the second sidelink HARQ feedback information. 9.The method of claim 8, wherein the first sidelink HARQ feedbackinformation and the second sidelink HARQ feedback information aremultiplexed.
 10. The method of claim 1, wherein the first indicatorfield indicates a physical sidelink feedback channel (PSFCH) to physicalHARQ timing.
 11. The method of claim 1, wherein the one or moreparameters indicates a size of a time window for transmitting sidelinkHARQ feedback information to the base station, and wherein the SL DCIindicates a slot, in the time window, for transmitting the firstsidelink HARQ feedback information to the base station.
 12. The methodof claim 1, further comprising: determining, based on the firstindicator field indicating a first value, that the first time intervaland the second time interval are in a same slot.
 13. A methodcomprising: receiving, by a wireless user device from a base station,one or more parameters associated with sidelink communication betweenwireless user devices; receiving, from the base station, sidelinkdownlink control information (SL DCI) comprising a first indicator fieldthat indicates a sidelink hybrid automatic repeat request (HARQ)feedback timing; after receiving the SL DCI, transmitting, to a secondwireless user device, a first sidelink signal via a physical sidelinkshared channel (PSSCH); during a first time interval, receiving, fromthe second wireless user device, first sidelink HARQ feedbackinformation responsive to the first sidelink signal; determining, basedon the sidelink HARQ feedback timing and based on the reception of thefirst sidelink HARQ feedback information, a second time interval,wherein the one or more parameters indicates information of a timewindow that comprises the second time interval, wherein the time windowcomprises a plurality of discontinuous time intervals, and wherein eachof the plurality of discontinuous time intervals corresponds to one ormore uplink slots; and during the second time interval, transmitting, tothe base station, the first sidelink HARQ feedback information.
 14. Themethod of claim 13, wherein: receiving the one or more parameterscomprises receiving one or more radio resource control (RRC) signalsindicating the one or more parameters; a bitwidth of the first indicatorfield is based on at least one of the one or more parameters; anddetermining the second time interval is based on the first timeinterval.
 15. The method of claim 13, further comprising: determining,based on at least one of the one or more parameters, a bitwidth of thefirst indicator field; and determining, based on the SL DCI and thedetermined bitwidth of the first indicator field, a value of the firstindicator field.
 16. The method of claim 15, wherein the value of thefirst indicator field is associated with a quantity of slots between afirst slot comprising the first time interval and a second slotcomprising the second time interval.
 17. The method of claim 13, furthercomprising: receiving, from the base station, one or more radio resourcecontrol (RRC) signals indicating at least one of: one or moresemi-static sidelink transmission resources; or a slot of a time windowfor transmitting sidelink HARQ feedback information to the base station.18. The method of claim 13, wherein the SL DCI further comprise aphysical uplink control channel (PUCCH) resource indicator fieldindicating one or more uplink resources for transmitting the firstsidelink HARQ feedback information to the base station.
 19. The methodof claim 13, wherein the one or more parameters indicate one or moretiming offset values associated with available timing offsets betweenthe first time interval and the second time interval, and wherein abitwidth of the first indicator field is determined based on a quantityof the one or more timing offset values.